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1

Thin film superconductor magnetic bearings  

DOEpatents

A superconductor magnetic bearing includes a shaft (10) that is subject to a load (L) and rotatable around an axis of rotation, a magnet (12) mounted to the shaft, and a stator (14) in proximity to the shaft. The stator (14) has a superconductor thin film assembly (16) positioned to interact with the magnet (12) to produce a levitation force on the shaft (10) that supports the load (L). The thin film assembly (16) includes at least two superconductor thin films (18) and at least one substrate (20). Each thin film (18) is positioned on a substrate (20) and all the thin films are positioned such that an applied magnetic field from the magnet (12) passes through all the thin films. A similar bearing in which the thin film assembly (16) is mounted on the shaft (10) and the magnet (12) is part of the stator (14) also can be constructed.

Weinberger, Bernard R. (Avon, CT)

1995-12-26

2

Fate of the Josephson effect in thin-film superconductors  

NASA Astrophysics Data System (ADS)

The d.c. Josephson effect refers to the dissipationless electrical current-the supercurrent-that can be sustained across a weak link connecting two bulk superconductors. This effect probes the nature of the superconducting state, which depends crucially on spatial dimensionality. For bulk (that is, three-dimensional) superconductors, the superconductivity is most robust and the Josephson effect is sustained even at non-zero temperature. However, in wires and thin films, thermal and quantum fluctuations play a crucial role. In superconducting wires, these effects qualitatively modify the electrical transport across a weak link. Despite several experiments involving weak links between thin-film superconductors, little theoretical attention has been paid to the electrical conduction in such systems. Here, we analyse the case of two superconducting thin films connected by a point contact. Remarkably, the Josephson effect is absent at non-zero temperature. The point-contact resistance is non-zero and varies with temperature in a nearly activated fashion, with a universal energy barrier set by the superfluid stiffness characterizing the films. This behaviour reflects the subtle nature of thin-film superconductors and should be observable in future experiments.

Hermele, Michael; Refael, Gil; Fisher, Matthew P. A.; Goldbart, Paul M.

2005-11-01

3

Thin film superconductors and process for making same  

DOEpatents

A process for the preparation of oxide superconductors from high-viscosity non-aqueous solution is described. Solutions of lanthanide nitrates, alkaline earth nitrates and copper nitrates in a 1:2:3 stoichiometric ratio, when added to ethylene glycol containing citric acid solutions, have been used to prepare highly viscous non-aqueous solutions of metal mixed nitrates-citrates. Thin films of these compositions are produced when a layer of the viscous solution is formed on a substrate and subjected to thermal decomposition.

Nigrey, P.J.

1988-01-21

4

Singular Limits for Thin Film Superconductors in Strong Magnetic Fields - Maan Field Model for Thin Films  

E-print Network

We consider singular limits of the three-dimensional Ginzburg-Landau functional for a superconductor with thin-film geometry, in a constant external magnetic field. The superconducting domain has characteristic thickness on the scale $\\eps>0$, and we consider the simultaneous limit as the thickness $\\eps\\rightarrow 0$ and the Ginzburg-Landau parameter $\\kappa\\rightarrow\\infty$. We assume that the applied field is strong (on the order of $\\eps^{-1}$ in magnitude) in its components tangential to the film domain, and of order $\\log\\kappa$ in its dependence on $\\kappa$. We prove that the Ginzburg-Landau energy $\\Gamma$-converges to an energy associated with a two-obstacle problem, posed on the planar domain which supports the thin film. The same limit is obtained regardless of the relationship between $\\eps$ and $\\kappa$ in the limit. Two illustrative examples are presented, each of which demonstrating how the curvature of the film can induce the presence of both (positively oriented) vortices and (negatively oriented) antivortices coexisting in a global minimizer of the energy.

Stan Alama; Lia Bronsard; Bernardo Galvão-Sousa

2012-09-17

5

Discriminator Stabilized Superconductor/Ferroelectric Thin Film Local Oscillator  

NASA Technical Reports Server (NTRS)

A tunable local oscillator with a tunable circuit that includes a resonator and a transistor as an active element for oscillation. Tuning of the circuit is achieved with an externally applied dc bias across coupled lines on the resonator. Preferably the resonator is a high temperature superconductor microstrip ring resonator with integral coupled lines formed over a thin film ferroelectric material. A directional coupler samples the output of the oscillator which is fed into a diplexer for determining whether the oscillator is performing at a desired frequency. The high-pass and lowpass outputs of the diplexer are connected to diodes respectively for inputting the sampled signals into a differential operational amplifier. The amplifier compares the sampled signals and emits an output signal if there is a difference between the resonant and crossover frequencies. Based on the sampled signal, a bias supplied to the ring resonator is either increased or decreased for raising or lowering the resonant frequency by decreasing or increasing, respectively, the dielectric constant of the ferroelectric.

Romanofsky, Robert R. (Inventor); Miranda, Felix A. (Inventor)

2000-01-01

6

Superconductor—Insulator Transitions in Pure Polycrystalline Nb Thin Films  

NASA Astrophysics Data System (ADS)

We report on a study of the transport properties of Nb thin films. By varying the thickness of the films from 263 Å to 25 Å, we observed a depression of the superconductivity. Magnetic field was also applied up to 6 T, inducing the disappearance of the superconductivity and the onset of an insulating behavior. The results were compared to those we have already obtained on a highly disordered system, a-NbxSi1-x, to understand whether the same mechanisms for the disappearance of the superconductivity could be at play in pure metallic thin films and in highly disordered systems.

Couedo, F.; Crauste, O.; Bergé, L.; Dolgorouky, Y.; Marrache-Kikuchi, C.; Dumoulin, L.

2012-12-01

7

Application of sol-gel techniques to thin-film superconductor systems  

SciTech Connect

This paper discusses the preparation and characterization of sol-gel produced thin films for barrier layer and high T{sub c} superconductor applications. Hydrolyzed metal alkoxide solutions were spin coated on Si substrates with subsequent thermal processing. Barrier layers of alkaline earth oxides, perovskites, Y{sub 2}O{sub 3}, ZrO{sub 2} and others were produced. Characterization was performed via SEM, XRD, ESCA, Auger depth profiling and four point probe resistivity measurements for 1-2-3 thin films. On Si wafers, barrier layer films were fairly smooth with some cracking and pitting present. Si migration was severe for alkaline earth thin films on Si wafers. Some perovskite films on Si showed formation of Ba-Si-O phases at the Si interface.

Wandass, J.H.; Cambria, F.M.; Whitwell, G.E. (Akzo Chemicals Inc., Akzo Research Laboratory Dobbs Ferry, Livingston Ave., Dobbs Ferry, NY (USA))

1990-01-25

8

Thickness-dependent pinning in a superconductor thin film Naval Surface Warfare Center, Carderock Division, Bethesda, Maryland 20817  

E-print Network

Thickness-dependent pinning in a superconductor thin film D. Agassia Naval Surface Warfare Center properties, is critical for the success of future efforts. In this work we consider another possible source

Pennycook, Steve

9

Microgravity annealing system for thin-film superconductors  

SciTech Connect

A mirror furnace system for annealing of superconducting thin films, which is adapted for the world's longest dropshaft completed at Kamisunagawa, Japan, is described. The system must be designed for completing both melting and solidification processes during a short 10-s microgravity period, and also for withstanding the deceleration of a drop capsule in which the furnace system is contained. All moving components must be operated so as not to disturb the microgravity environment. A random vibration test for the entire system was carried out before the microgravity experiment, and structural compatibility was verified. The furnace system worked well, and the accumulated number of free falls was 19. Results of annealing of the superconducting material at one gravity and microgravity were compared using scanning electron microscopy and x-ray microanalysis.

Murakami, H.; Hosokawa, S.; Kudo, I.; Endo, K.; Yoshida, S. (Electrotechnical Laboratory, 1-1-4 Umezono, Tsukuba 305, Ibaraki (Japan)); Ichikawa, Y.; Setsune, K.; Teramoto, A. (Japan Space Utilization Promotion Center, 2-21-16 Nishi-Waseda, Shinjuku 169, Tokyo (Japan))

1993-06-01

10

Application of sol-gel techniques to thin-film superconductor systems  

NASA Astrophysics Data System (ADS)

This paper discusses the preparation and characterization of sol-gel produced thin films for barrier layer and high Tc superconductor applications. Hydrolyzed metal alkoxide solutions were spin coated on Si substrates with subsequent thermal processing. Barrier layers of alkaline earth oxides, perovskites, Y2O3, ZrO2 and others were produced. Characterization was performed via SEM, XRD, ESCA, Auger depth profiling and four point probe resistivity measurements for 1-2-3 thin films. On Si wafers, barrier layer films were fairly smooth with some cracking and pitting present. Si migration was severe for alkaline earth thin films on Si wafers. Some perovskite films on Si showed formation of Ba-Si-O phases at the Si interface. Thin films of 1-2-3 on sol-gel produced barrier layers of SrTiO3 or ZrO2 on Si showed Ba pileup at the Si interface and were not superconducting. 1-2-3 layers deposited on single crystal ZrO2 were superconducting and showed onset temperatures of 90 K with zero resistance reached at about 55 K. SEM morphology differences were observed for the different 1-2-3 preparations.

Wandass, J. H.; Cambria, F. M.; Whitwell, G. E.

1990-01-01

11

High T(sub c) thin film superconductors: Preparation, patterning and characterization  

NASA Astrophysics Data System (ADS)

A conventional oil-pumped vacuum system equipped with resistively heated tungsten boat sources was used for evaporation of bismuth- or yttrium-based cuprates for high T(sub c) thin film superconductors. A well-ground mixture with atomic proportions of bismuth, SrF2, CaF2 and copper for bismuth-based material, and of YF3, BaF2 and copper for yttrium-based material, was inserted into the boat and then resistively evaporated onto different substrates such as MgO, ZrO2 and SrTiO3 kept at room temperature. Yttrium-based thin films were found to have a better quality upon reduction of fluorine in the constituents. Thus, films prepared with an yttrium BaF2 and copper mixture show a metallic-like behavior, sharper transition and higher zero-resistance temperature as compared with that of films obtained by using a YF2 constiuent instead of yttrium. Bismuth-based thin films were found to lose bismuth during heat treatment unless the copper constiuent ended the evaporation process and was subsequently fully oxidized at 400 C. Bismuth-based patterned films were easily obtained by using a lift-off photolithographic method. Typical thickness of the films was measured to be about 0.5 micron after heat treatment.

Azoulay, J.

12

A Novel Method for Characterization of Superconductors: Physical Measurements and Modeling of Thin Films  

NASA Technical Reports Server (NTRS)

A method for characterization of granular superconducting thin films has been developed which encompasses both the morphological state of the sample and its fabrication process parameters. The broad scope of this technique is due to the synergism between experimental measurements and their interpretation using numerical simulation. Two novel technologies form the substance of this system: the magnetically modulated resistance method for characterizing superconductors; and a powerful new computer peripheral, the Parallel Information Processor card, which provides enhanced computing capability for PC computers. This enhancement allows PC computers to operate at speeds approaching that of supercomputers. This makes atomic scale simulations possible on low cost machines. The present development of this system involves the integration of these two technologies using mesoscale simulations of thin film growth. A future stage of development will incorporate atomic scale modeling.

Kim, B. F.; Moorjani, K.; Phillips, T. E.; Adrian, F. J.; Bohandy, J.; Dolecek, Q. E.

1993-01-01

13

Investigations of High-Temperature Superconductors and Magnetic Thin Films  

NASA Astrophysics Data System (ADS)

Magnetic, structural, and superconducting properties of three classes of Fe-doped high temperature superconductors and magnetic properties in the surface regions of a thick Fe(110) layer with an MnF_2 interface have been studied. The three classes of Fe-doped high -T_{c} superconductors are: (1) GdBa_2Cu_3O_ {7-delta}, (2) La_ {2-x}Sr_{x}CuO _4, and (3) Bi_2Sr _2Ca_{n} Cu_{n+1}O _{x} with n = 1 and 2. Fe doping in the rm GdBa_2Cu _3O_{7-delta} materials not only depresses the global superconducting transition temperature but also destroys superconductivity in small regions localized around the Fe impurities. Short-range spin correlations among the Cu spins are observed in these regions at low temperatures. As the oxygen content is gradually reduced, the short-range spin correlations evolve into a long-range 3D antiferromagnetic ordering. Structurally, the Fe impurities tend to suppress the orthorhombic distortion. About 90% of the Fe dopants reside at the Cu(1) sites. The spin and charge states of the Fe dopants along with their oxygen coordination configurations are determined. This has allowed us to understand the microscopic origin of the structural changes due to Fe doping. The correlation between the T _{c} depression and structural change suggests that the linear Cu(1)-O chains are important for the high temperature superconductivity in this system. The magnetic dynamics of rm La_2CuO _4 is investigated using the magnetic Fe ^{3+} ions as a probe. The temperature dependence of the sublattice magnetization shows a 3D-2D dimensional crossover characteristic of a highly anisotropic antiferromagnet. The existence of extra oxygens in the La-O bilayers in O_2 -annealed rm La_2CuO_{4+ delta} samples is demonstrated. Fe doping in the rm La_{1.85}Sr_ {0.15}CuO_4 samples is found to be pur extremely detrimental to superconductivity. The optimal compositions and sintering conditions for producing single-phase ~85 K Bi-Sr-Ca-Cu superconductors are explored. The Ca content is extremely important to the ~85 K superconductivity. Significant local structural irregularities in the ~85 K phase due to various types of structural defects are observed. The effect of Fe doping on T_{c} is comparable to that of the rm GdBa_2Cu _3O_{7-delta} system, but much weaker than that of the rm La_ {1.85}Sr_{0.15}O_4 system. This indicates that the interlayer coupling between superconducting Cu-O_2 planes in the Bi-Sr-Ca-Cu and the 1-2-3 systems is important. The anomalous quasilinear temperature dependence of magnetization is found to persist at least 13 monolayers into the interior of a thick Fe(110) layer with an MnF _2 interface. The result is compared with a recent surface-anisotropy-based model. Similar anomalous magnetic behavior observed in the surface regions of a closely related system suggests that the antiferromagnetic nature of the cover material MnF_2 may be responsible for the anomalous magnetic behavior.

Tang, Huan

1991-02-01

14

Optical properties of TiN thin films close to the superconductor-insulator transition.  

SciTech Connect

We present the intrinsic optical properties over a broad spectral range of TiN thin films deposited on an Si/SiO{sub 2} substrate. We analyze the measured reflectivity spectra of the film-substrate multilayer structure within a well-establish procedure based on the Fresnel equation and extract the real part of the optical conductivity of TiN. We identify the metallic contribution as well as the finite energy excitations and disentangle the spectral weight distribution among them. The absorption spectrum of TiN bears some similarities with the electrodynamic response observed in the normal state of the high-temperature superconductors. Particularly, a mid-infrared feature in the optical conductivity is quite reminiscent of a pseudogap-like excitation.

Pfuner, F.; Degiorgi, L.; Baturina, T. I.; Vinokur, V. M.; Baklanov, M. R.; Materials Science Division; ETH Zurich; Inst. Semiconductor Physics; IMEC Kapeldreef

2009-11-10

15

Combined time-resolved magneto-optical and electrical flux detection in thin-film superconductors  

SciTech Connect

The dynamic behavior of the current-induced dissipative flux-flow state in a thin-film type I superconductor was studied by simultaneous stroboscopic magneto-optical flux detection and direct recording of the time-resolved flux-flow voltage. Employing high-resolution magneto-optical flux detection with a high-speed stroboscope, it was possible to visualize globally individual multiquantum flux tubes during their rapid motion across the superconducting Pb film, yielding spatial and temporal resolution of better than 1 ..mu..m and 0.1 ..mu..sec, respectively. Simultaneously, the temporal structure of the flux-flow voltage was recorded using a highly sensitive signal-averaging procedure, thereby yielding a voltage resolution of about 30 nV at a time resolution of 10 nsec (corresponding to a recording bandwidth of 25 MHz). The recorded temporal voltage structures agreed well with the voltages expected from the velocity profiles of all flux tubes existing simultaneously obtained from the magneto-optical data. The experiments are the first to demonstrate full agreement between both independent flux-detection measurements, clearly confirming the existing theory.

Parisi, J.; Muehlemeier, B.; Huebener, R.P.; Buck, W.

1985-07-01

16

Internal Vortex Structure Change in a Thin Film for an Unconventional Superconductor  

NASA Astrophysics Data System (ADS)

The vortex structure of an unconventional superconductor in a thinfilm is investigated using the example of a two-components orderparameter. Under certain conditions such vortices do not posses a normal core. In this case, our theory shows an anomaly in the Hc1 (for fields paralle to the film) as a function oftemperature or film thickness. The origin of this anomaly lies in structural transition of the vortex which leads to thestabilization of fractional vortices in the film.

Ogawa, Nobuyuki; Sigrist, Manfred; Ueda, Kazuo

1996-02-01

17

Thin film growth of Fe-based superconductors: from fundamental properties to functional devices. A comparative review  

NASA Astrophysics Data System (ADS)

Fe-based superconductors bridge a gap between MgB2 and the cuprate high temperature superconductors as they exhibit multiband character and transition temperatures up to around 55 K. Investigating Fe-based superconductors thus promises answers to fundamental questions concerning the Cooper pairing mechanism, competition between magnetic and superconducting phases, and a wide variety of electronic correlation effects. The question addressed in this review is, however, is this new class of superconductors also a promising candidate for technical applications? Superconducting film-based technologies range from high-current and high-field applications for energy production and storage to sensor development for communication and security issues and have to meet relevant needs of today's society and that of the future. In this review we will highlight and discuss selected key issues for Fe-based superconducting thin film applications. We initially focus our discussion on the understanding of physical properties and actual problems in film fabrication based on a comparison of different observations made in the last few years. Subsequently we address the potential for technological applications according to the current situation.

Haindl, S.; Kidszun, M.; Oswald, S.; Hess, C.; Büchner, B.; Kölling, S.; Wilde, L.; Thersleff, T.; Yurchenko, V. V.; Jourdan, M.; Hiramatsu, H.; Hosono, H.

2014-04-01

18

Thin film growth of Fe-based superconductors: from fundamental properties to functional devices. A comparative review.  

PubMed

Fe-based superconductors bridge a gap between MgB2 and the cuprate high temperature superconductors as they exhibit multiband character and transition temperatures up to around 55 K. Investigating Fe-based superconductors thus promises answers to fundamental questions concerning the Cooper pairing mechanism, competition between magnetic and superconducting phases, and a wide variety of electronic correlation effects. The question addressed in this review is, however, is this new class of superconductors also a promising candidate for technical applications? Superconducting film-based technologies range from high-current and high-field applications for energy production and storage to sensor development for communication and security issues and have to meet relevant needs of today’s society and that of the future. In this review we will highlight and discuss selected key issues for Fe-based superconducting thin film applications. We initially focus our discussion on the understanding of physical properties and actual problems in film fabrication based on a comparison of different observations made in the last few years. Subsequently we address the potential for technological applications according to the current situation. PMID:24695004

Haindl, S; Kidszun, M; Oswald, S; Hess, C; Buchner, B; Kolling, S; Wilde, L; Thersleff, T; Yurchenko, V V; Jourdan, M; Hiramatsu, H; Hosono, H

2014-04-01

19

Fabrication of high T(sub c) superconductor thin film devices: Center director's discretionary fund  

NASA Technical Reports Server (NTRS)

This report describes a technique for fabricating superconducting weak link devices with micron-sized geometries etched in laser ablated Y1Ba2Cu3O(x) (YBCO) thin films. Careful placement of the weak link over naturally occurring grain boundaries exhibited in some YBCO thin films produces Superconducting Quantum Interference Devices (SQUID's) operating at 77 K.

Sisk, R. C.

1992-01-01

20

Method for forming single phase, single crystalline 2122 BCSCO superconductor thin films by liquid phase epitaxy  

NASA Technical Reports Server (NTRS)

A substantially single phase, single crystalline, highly epitaxial film of Bi.sub.2 CaSr.sub.2 Cu.sub.2 O.sub.8 superconductor which has a T.sub.c (zero resistance) of 83 K is provided on a lattice-matched substrate with no intergrowth. This film is produced by a Liquid Phase Epitaxy method which includes the steps of forming a dilute supercooled molten solution of a single phase superconducting mixture of oxides of Bi, Ca, Sr, and Cu having an atomic ratio of about 2:1:2:2 in a nonreactive flux such as KCl, introducing the substrate, e.g., NdGaO.sub.3, into the molten solution at 850.degree. C., cooling the solution from 850.degree. C. to 830.degree. C. to grow the film and rapidly cooling the substrate to room temperature to maintain the desired single phase, single crystalline film structure.

Pandey, Raghvendra K. (Inventor); Raina, Kanwal (Inventor); Solayappan, Narayanan (Inventor)

1994-01-01

21

Epitaxial layers of 2122 BCSCO superconductor thin films having single crystalline structure  

NASA Technical Reports Server (NTRS)

A substantially single phase, single crystalline, highly epitaxial film of Bi.sub.2 CaSr.sub.2 Cu.sub.2 O.sub.8 superconductor which has a T.sub.c (zero resistance) of 83K is provided on a lattice-matched substrate with no intergrowth. This film is produced by a Liquid Phase Epitaxy method which includes the steps of forming a dilute supercooled molten solution of a single phase superconducting mixture of oxides of Bi, Ca, Sr, and Cu having an atomic ratio of about 2:1:2:2 in a nonreactive flux such as KCl, introducing the substrate, e.g., NdGaO.sub.3, into the molten solution at 850.degree. C., cooling the solution from 850.degree. C. to 830.degree. C. to grow the film and rapidly cooling the substrate to room temperature to maintain the desired single phase, single crystalline film structure.

Pandey, Raghvendra K. (Inventor); Raina, Kanwal K. (Inventor); Solayappan, Narayanan (Inventor)

1995-01-01

22

Simultaneous magnetic and transport currents in thin film superconductors within the critical-state approximation  

NASA Astrophysics Data System (ADS)

We calculate the current distribution present in superconducting planar thin films of different geometries including strips with slits, ? /2-turns, and widenings. We consider simultaneous application of external transport electric current and perpendicular magnetic field and systematically obtain the current distribution. From the calculations we show how, based on different sequences of the externally applied magnitudes, one can control the current distribution in the thin sample.

Via, Guillem; Del-Valle, Nuria; Sanchez, Alvaro; Navau, Carles

2015-01-01

23

Critical behavior of superconductors and electrical transport properties of carbon nanotube thin films  

Microsoft Academic Search

With AC microwave measurements from 10 MHz up to 50 GHz and DC nanovolt level measurements we have investigated the superconducting phase transition of YBa2Cu3O7-delta films in zero magnetic field and electrical transport properties of single walled carbon nanotube networks. We studied the microwave conductivity of YBa2Cu3O 7-delta thin films around Tc for different incident microwave power and observed that

Hua Xu

2007-01-01

24

Interface Spin-Orbit Coupling in a Non-centrosymmetric Thin-Film Superconductor X. S. Wu and P. W. Adams  

E-print Network

Interface Spin-Orbit Coupling in a Non-centrosymmetric Thin-Film Superconductor X. S. Wu and P. W of the effects of interface spin-orbit coupling (ISOC) on the critical field behavior of non-centrosymmetric (NCS. In addition, the parallel critical field unexpectedly scaled as Hc||/o 1/d suggesting that the spin-orbit

Adams, Philip W.

25

Thin film seeds for melt processing textured superconductors for practical applications  

DOEpatents

A method of fabricating bulk superconducting material such as RBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} where R is La or Y comprising depositing a thin epitaxially oriented film of Nd or Sm (123) on an oxide substrate is disclosed. The powder oxides of RBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} or oxides and/or carbonates of R and Ba and Cu present in mole ratios to form RBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}, where R is Y or La are heated, in physical contact with the thin film of Nd or Sm (123) on the oxide substrate to a temperature sufficient to form a liquid phase in the oxide or carbonate mixture while maintaining the thin film solid to grow a large single domain 123 superconducting material. Then the material is cooled. The thin film is between 200 {angstrom} and 2000 {angstrom}. A construction prepared by the method is also disclosed.

Veal, B.W.; Paulikas, A.; Balachandran, U.; Zhong, W.

1999-02-09

26

Substrate effect on thermal stability of superconductor thin films in the peritectic melting.  

PubMed

Systematic experiments were performed by in situ observation of the YBa(2)Cu(3)O(z) (Y123 or YBCO) melting. Remarkably, the superheating phenomenon was identified to exist in all commonly used YBCO thin films, that is, films deposited on MgO, LaAlO(3) (LAO), and SrTiO(3) (STO) substrates, suggesting a universal superheating mode of the YBCO film. Distinctively, YBCO/LAO films were found to possess the highest level of superheating, over 100 K, mainly attributed to the lattice match effect of LAO substrate, that is, its superior lattice fit with Y123 delaying the Y123 dissolving and inferior lattice matching with Y(2)BaCuO(5) (Y211) delaying the Y211 nucleation. Moreover, strong dependence of the thermal stability on the substrate material for Y123 films was also found to be associated with the substrate wettability by the liquid and the potential element doping from the substrate. Most importantly, the understanding of the superheating behavior is widely valid for more film/substrate constructions that have the same nature as the YBCO film/substrate. PMID:22540312

Chen, Y Y; Fang, T F; Yan, S B; Yao, X; Tao, B W

2012-05-31

27

Sequentially evaporated thin Y-Ba-Cu-O superconductor films: Composition and processing effects  

NASA Technical Reports Server (NTRS)

Thin films of YBa2Cu3O(7-beta) have been grown by sequential evaporation of Cu, Y, and BaF2 on SrTiO3 and MgO substrates. The onset temperatures were as high as 93 K while T sub c was 85 K. The Ba/Y ratio was varied from 1.9 to 4.0. The Cu/Y ratio was varied from 2.8 to 3.4. The films were then annealed at various times and temperatures. The times ranged from 15 min to 3 hr, while the annealing temperatures used ranged from 850 C to 900 C. A good correlation was found between transition temperature (T sub c) and the annealing conditions; the films annealed at 900 C on SrTiO3 had the best T sub c's. There was a weaker correlation between composition and T sub c. Barium poor films exhibitied semiconducting normal state resistance behavior while barium rich films were metallic. The films were analyzed by resistance versus temperature measurements and scanning electron microscopy. The analysis of the films and the correlations are reported.

Valco, George J.; Rohrer, Norman J.; Warner, Joseph D.; Bhasin, Kul B.

1988-01-01

28

A New Technique for Studying the Pinning Force on a Single Vortex in a Thin-Film Superconductor  

NASA Astrophysics Data System (ADS)

We have developed a new SQUID-based technique for studying the pinning of a single vortex in a superconducting thin film patterned into a cross shape. Ends of each strip are connected via superconducting wires to the input coils of two SQUIDs, forming superconducting inductive loops. The vortex is trapped by heating the intersection of the cross above its critical temperature with a laser pulse.(G.S. Park, C.E. Cunningham, B. Cabrera, and M.E. Huber, J. Appl. Phys. 73 (1993) 2419.) The vortex is detected and its position measured by a shift in the quantization currents in the loops coupled to the SQUIDs. This technique provides a combination of good temporal and spatial resolution of the vortex position. By sending currents through both strips, we can exert on the vortex a Magnus force in any direction, and we can detect its motion in the superconductor with the SQUIDs. We are using this technique to study flux motion between pinning sites and to measure the temperature-dependence of the pinning force in thin-film niobium.

Cunningham, Charles E.; de Young, Tyce; Cochran, Matthew; Rinehart, Adam; Peterson, Sarah; Andrews, Timothy

1998-03-01

29

thin films  

NASA Astrophysics Data System (ADS)

Optical scattering properties of nanostructured matter have crucial impact on performance efficiency of various photonic components, such as waveguides, display elements, and solar cells. In this paper, diffuse transmission properties of nanocrystalline Pb(Zr x Ti1- x )O3 thin films with a high refractive index of ~2.5 and optical transmittance are presented. Thin films with a thicknesses ranging from 50 to 500 nm were studied using integrating sphere technique and results were compared to simulations performed by a scalar scattering theory. Thin films were deposited by pulsed laser deposition at room temperature on MgO(100) substrates and post-annealed at a temperature of 800 °C. Structural phase evolution-induced surface effects, which introduced periodicity on the film surface, cause the definite diffuse elements in transmission spectra of the films. Low and evenly distributed scattering amplitudes in k-space were seen for highly tetragonal- or trigonal-oriented films with non-textured surfaces, which led to low diffuse transmission values ( T D ? 5 %), while confined and increased scattering amplitudes in k-space were seen for tetragonal-trigonal-oriented films, with phase co-existence, which led to microstructure-induced textured surfaces and increased diffuse transmission values ( T D ? 50 %). For highly textured surfaces, scattering amplitudes distributed in tilted ellipsoid shape in k-space was observed. Difference between modeled and measured values was 3.8 % in maximum.

Puustinen, Jarkko; Lappalainen, Jyrki; Hiltunen, Jussi; Hiltunen, Marianne

2014-07-01

30

Thin Films  

NASA Astrophysics Data System (ADS)

Effect of annealing temperature on the characteristics of sol-gel-driven Ta ax La(1- a) x O y thin film spin-coated on Si substrate as a high- k gate dielectric was studied. Ta ax La(1- a) x O y thin films with different amounts of a were prepared (as-prepared samples). X-ray diffraction measurements of the as-prepared samples indicated that Ta0.3 x La0.7 x Oy film had an amorphous structure. Therefore, Ta0.3 x La0.7 x O y film was chosen to continue the present studies. The morphology of Ta0.3 x La0.7 x O y films was studied using scanning electron microscopy and atomic force microscopy techniques. The obtained results showed that the size of grain boundaries on Ta0.3 x La0.7 x O y film surfaces was increased with increasing annealing temperature. Electrical and optical characterizations of the as-prepared and annealed films were investigated as a function of annealing temperature using capacitance-voltage ( C- V) and current density-voltage ( J- V) measurements and the Tauc method. The obtained results demonstrated that Ta0.3 x La0.7 x O y films had high dielectric constant (?27), wide band gap (?4.5 eV), and low leakage current density (?10-6 A/cm2 at 1 V).

Khorshidi, Zahra; Bahari, Ali; Gholipur, Reza

2014-11-01

31

Ferromagnetic SrRuO3 thin-film deposition on a spin-triplet superconductor Sr2RuO4 with a highly conducting interface  

NASA Astrophysics Data System (ADS)

Ferromagnetic SrRuO3 thin films are deposited on the ab surface of single crystals of the spin-triplet superconductor (TSC) Sr2RuO4 as substrates using pulsed laser deposition. The films are under a severe in-plane compressive strain. Nevertheless, the films exhibit ferromagnetic order with the easy axis along the c-direction below the Curie temperature of 158 K. The electrical transport reveals that the SrRuO3/Sr2RuO4 interface is highly conducting, in contrast with the interface between other normal metals and the ab surface of Sr2RuO4. Our results stimulate investigations on proximity effects between a ferromagnet and a TSC.

Anwar, M. S.; Shin, Yeong Jae; Lee, Seung Ran; Kang, Sung Jin; Sugimoto, Yuske; Yonezawa, Shingo; Noh, Tae Won; Maeno, Yoshiteru

2015-01-01

32

5. SUPERCONDUCTOR-METAL-INSULATOR TRANSITIONS: Vortex states at low temperature in disordered thin and thick films of a-MoxSi1-x  

NASA Astrophysics Data System (ADS)

We have measured the ac complex resistivity in the linear regime, as well as dc resistivity, for thick (100, 300 nm) amorphous (a-)MoxSi1-x films at low temperatures (T > 0.04 K) in constant fields B. The critical behavior associated with the second-order transition has been observed for both dc and ac resistivities, which is similar to that observed for granular indium films. This is the first convincing evidence for the vortex glass transition (VGT) in the homogeneously disordered low-TC superconductors containing microscopic pinning centers. We have found that the VGT persists down to T ~ 0.1TC0 up to B ~ 0.9BC2(0), where TC0 and BC2(0) are the mean-field transition temperature and upper critical field at T = 0, respectively. At T ? 0 the VGT line Bg(T) extrapolates to a field below BC2(0), indicative of the presence of a T = 0 quantum-vortex-liquid phase in the region Bg(0) < B < BC2(0). For thin (4 nm) films the (T = 0) field-driven superconductor-insulator transition takes place at BC. We have not obtained evidence of the metallic quantum liquid phase below BC, while in B > BC an anomalous negative magnetoresistance (MR) suggesting the presence of the localized Cooper pairs has been observed. The negative MRis commonly observed for thin films; however, for thick films the MR is always positive. This means that the two-dimensionality plays an important role in the appearance of the negative MR (or localized Cooper pairs). The negative MR is no longer visible as the field is applied parallel to the film surface, consistent with the view that mobile vortices, as well as localized Cooper pairs, are present in B > BC.

Okuma, S.; Morita, M.

2001-10-01

33

Thin Films  

NASA Astrophysics Data System (ADS)

Titanium dioxide (TiO2) thin films were synthesized on glass substrates by spray pyrolysis. The effect of solution flow rate on the physical properties of the films was investigated by use of x-ray diffraction (XRD), scanning electron microscopy, atomic force microscopy (AFM), and spectrophotometry techniques. XRD analysis revealed the tetragonal anatase phase of TiO2 with highly preferred (101) orientation. AFM images showed that grain size on top of TiO2 thin films depended on solution flow rate. An indirect band gap energy of 3.46 eV was determined by means of transmission and reflection measurements. The envelope method, based on the optical transmission spectrum, was used to determine film thickness and optical constants, for example real and imaginary parts of the dielectric constant, refractive index, and extinction coefficient. Ultraviolet and visible photoluminescence emission peaks were observed at room temperature. These peaks were attributed to the intrinsic emission and to the surface defect states, respectively.

Naffouti, Wafa; Nasr, Tarek Ben; Mehdi, Ahmed; Kamoun-Turki, Najoua

2014-11-01

34

Proximity effects at the interface of a superconductor and a topological insulator in NbN-Bi2Se3 thin film bilayers  

NASA Astrophysics Data System (ADS)

In a search for a simple proximity system of a topological insulator and a superconductor for studying the role of surface versus bulk effects by gating, we report here on a first step toward this goal, namely the choice of such a system and its characterization. We chose to work with thin film bilayers of grainy 5 nm thick NbN films as the superconductor, overlayed with 20 nm thick topological layer of B{{i}2}S{{e}3} and compare the transport results to those obtained on a 5 nm thick reference NbN film on the same wafer. Bilayers with ex situ and in situ prepared NbN-B{{i}2}S{{e}3} interfaces were studied and two kinds of proximity effects were found. At high temperatures just below the superconducting transition, all bilayers showed a conventional proximity effect where the topological B{{i}2}S{{e}3} suppresses the onset or mid-transition Tc of the superconducting NbN films by about 1 K. At low temperatures, a cross-over of the resistance versus temperature curves of the bilayer and reference NbN film occurs, where the bilayers show enhancement of {{T}c}(R=0), Ic (the supercurrent) and the Andreev conductance, as compared to the bare NbN films. This indicates that superconductivity is induced in the B{{i}2}S{{e}3} layer at the interface region in between the NbN grains. Thus an inverse proximity effect in the topological material is demonstrated.

Koren, Gad

2015-02-01

35

Techniques for Connecting Superconducting Thin Films  

NASA Technical Reports Server (NTRS)

Several improved techniques for connecting superconducting thin films on substrates have been developed. The techniques afford some versatility for tailoring the electronic and mechanical characteristics of junctions between superconductors in experimental electronic devices. The techniques are particularly useful for making superconducting or alternatively normally conductive junctions (e.g., Josephson junctions) between patterned superconducting thin films in order to exploit electron quantum-tunneling effects. The techniques are applicable to both low-Tc and high-Tc superconductors (where Tc represents the superconducting- transition temperature of a given material), offering different advantages for each. Most low-Tc superconductors are metallic, and heretofore, connections among them have been made by spot welding. Most high-Tc superconductors are nonmetallic and cannot be spot welded. These techniques offer alternatives to spot welding of most low-Tc superconductors and additional solutions to problems of connecting most high-Tc superconductors.

Mester, John; Gwo, Dz-Hung

2006-01-01

36

Self-ordering of random intercalates in thin films of cuprate superconductors: Growth model and x-ray diffraction diagnosis  

SciTech Connect

We propose a simple model for the nucleation of random intercalates during the growth of high-temperature superconductor (HTSC) films by pulsed laser deposition (PLD). The model predicts a very particular spatial distribution of defects: a Markovian-like sequence of displacements along the growth direction (c axis), as well as a two-component in-plane correlation function, characteristic of self-organized intercalates. A model for x-ray diffraction (XRD) on such structures is also developed and accounts for both c-axis and in-plane anomalies observed in XRD experiments. The method presented in this work constitutes a useful characterization tool in the optimization of deposition parameters for the growth of HTSC films.

Ariosa, D.; Cancellieri, C.; Pavuna, D. [Laboratory of X-ray, EPFL SB-IPMC-LPRX, CH-1015 Lausanne (Switzerland); Lin, P. H. [Laboratory of X-ray, EPFL SB-IPMC-LPRX, CH-1015 Lausanne (Switzerland); Department of Engineering and System Science, National Tsing Hua University, TW-30013, Taiwan (China); Academia Sinica, Institute of Physics, TW-11529, Taiwan (China)

2007-05-01

37

Materials research, superconductor and thin layer technology  

NASA Astrophysics Data System (ADS)

Materials research into polymer electric conductors, organic and inorganic polymer microspheres for chromatography, electronic gas sensor corrosion protection of historic glass windows, soldering of ceramics and metals, fiber reinforced automobile parts, superconductors, and thin layer technology is summarized.

1987-11-01

38

Low frequency resistance fluctuations in films of high temperature superconductors  

Microsoft Academic Search

Low-frequency voltage fluctuations in thin films of YBa2Cu3O(7-x) at and above the superconducting transition temperature have a spectral density proportional to the ratio of the average voltage across the film to the frequency. The ratio of the spectral density to the average voltage decreases markedly as the microstructure of the films is improved. In contrast to classic superconductors, the noise

P. Rosenthal; R. H. Hammond; M. R. Beasley; R. Leoni; Ph. Lerch; J. Clarke

1989-01-01

39

Thin Film Interference Model  

NSDL National Science Digital Library

The Thin Film Interference model investigates reflection and transmission of light through a thin film. The user can change the thickness and index of refraction of the thin film as well as the incident light wavelength. The Thin Film Interference Model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_bu_ThinFilm.jar file will run the program if Java is installed.

Duffy, Andrew

2010-04-25

40

The effect of grain size on the fluctuation-induced conductivity of Cu1-xTlxBa2Ca3Cu4O12-? superconductor thin films  

NASA Astrophysics Data System (ADS)

The high temperature superconductor thin films Cu1-xTlxBa2Ca3Cu4O12-? (Cu1-xTlx- 1234) are post-annealed in a nitrogen atmosphere. The zero-resistivity critical temperature (Tc(R = 0)) of these thin films is increased from 92.3 to 104 K. The grain size is enhanced and their morphology is improved with the post-annealing. The enlargement of grain size is linked to fluctuation-induced conductivity (FIC) in the light of Aslamazov-Larkin (AL) theory. The FIC measurements have shown that the cross-over of three-dimensional (3D) to two-dimensional (2D) behaviour of fluctuations is shifted to higher temperature values with an increase of post-annealing temperature. These results have shown that the removal of oxygen and the increased grain size are the most likely sources of the increase in the cross-over temperature, T* to higher values.

Khurram, A. A.; Mumtaz, M.; Khan, Nawazish A.; Ahadian, M. M.; Iraji-zad, Azam

2007-08-01

41

Investigation of magnetic proximity effect in ferromagnet/superconductor thin films by low temperature Magneto Optical Kerr Effect measurement.  

E-print Network

?? A room temperature Magneto Optical Kerr Effect (MOKE) experimental setup was expanded to improve performance and integrated with a liquid Helium cryogenic system. Ferromagnetic/superconductor… (more)

Christiansen, David A.

2013-01-01

42

Thin Film Technology: Adhesion in Thin Films  

SciTech Connect

Last month I addressed the subject of pinholes in thin films and ways to minimize them. The subject this month is another cause for success, or failure, of thin films, adhesion. I was motivated to discuss this horrendously complicated subject by a conference I recently attended, Adhesion Aspects of Thin Films (Orlando, December 15-17). This conference, organized by Dr.'s K.L. Mittal and R.H. Lacombe, was both stimulating and informative.

Martin, Peter M.

2004-02-01

43

Absence of a Proximity Effect for a Thin-Films of a Bi2Se3 Topological Insulator Grown on Top of a Bi2Sr2CaCu2O8+? Cuprate Superconductor  

NASA Astrophysics Data System (ADS)

Proximity-induced superconductivity in a 3D topological insulator represents a new avenue for observing zero-energy Majorana fermions inside vortex cores. Relatively small gaps and low transition temperatures of conventional s-wave superconductors put hard constraints on these experiments. Significantly larger gaps and higher transition temperatures in cuprate superconductors might be an attractive alternative to considerably relax these constraints, but it is not clear whether the proximity effect would be effective in heterostructures involving cuprates and topological insulators. Here, we present angle-resolved photoemission studies of thin Bi2Se3 films grown in situ on optimally doped Bi2Sr2CaCu2O8+? substrates that show the absence of proximity-induced gaps on the surfaces of Bi2Se3 films as thin as a 1.5 quintuple layer. These results suggest that the superconducting proximity effect between a cuprate superconductor and a topological insulator is strongly suppressed, likely due to a very short coherence length along the c axis, incompatible crystal and pairing symmetries at the interface, small size of the topological surface state's Fermi surface, and adverse effects of a strong spin-orbit coupling in the topological material.

Yilmaz, T.; Pletikosi?, I.; Weber, A. P.; Sadowski, J. T.; Gu, G. D.; Caruso, A. N.; Sinkovic, B.; Valla, T.

2014-08-01

44

Absence of a proximity effect for a thin-films of a Bi2Se3 topological insulator grown on top of a Bi2Sr2CaCu2O(8+?) cuprate superconductor.  

PubMed

Proximity-induced superconductivity in a 3D topological insulator represents a new avenue for observing zero-energy Majorana fermions inside vortex cores. Relatively small gaps and low transition temperatures of conventional s-wave superconductors put hard constraints on these experiments. Significantly larger gaps and higher transition temperatures in cuprate superconductors might be an attractive alternative to considerably relax these constraints, but it is not clear whether the proximity effect would be effective in heterostructures involving cuprates and topological insulators. Here, we present angle-resolved photoemission studies of thin Bi(2)Se(3) films grown in situ on optimally doped Bi(2)Sr(2)CaCu(2)O(8+?) substrates that show the absence of proximity-induced gaps on the surfaces of Bi(2)Se(3) films as thin as a 1.5 quintuple layer. These results suggest that the superconducting proximity effect between a cuprate superconductor and a topological insulator is strongly suppressed, likely due to a very short coherence length along the c axis, incompatible crystal and pairing symmetries at the interface, small size of the topological surface state's Fermi surface, and adverse effects of a strong spin-orbit coupling in the topological material. PMID:25148345

Yilmaz, T; Pletikosi?, I; Weber, A P; Sadowski, J T; Gu, G D; Caruso, A N; Sinkovic, B; Valla, T

2014-08-01

45

Investigation into the growth and structure of thin-film solid solutions of iron-based superconductors in the FeSe{sub 0.92}-FeSe{sub 0.5}Te{sub 0.5} system  

SciTech Connect

Thin films of FeSe{sub 0.92} and FeSe{sub 0.5}Te{sub 0.5} iron chalcogenide superconductors and solid solutions containing these components in different ratios have been grown on the surface of LaAlO{sub 3} (10 1-bar 2) crystals by pulsed laser deposition. Films of solid solutions have been deposited by simultaneous laser ablation from two targets of the FeSe{sub 0.92} and FeSe{sub 0.5}Te{sub 0.5} stoichiometric compositions onto one substrate. An X-ray diffraction study of the film structure shows that the films grown are epitaxial and their lattice parameters regularly vary with the ratio of the deposited components, which was controllably varied by changing the ablation intensities from the targets.

Stepantsov, E. A., E-mail: stepantsov@ns.cryst.ras.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Kazakov, S. M.; Belikov, V. V. [Moscow State University (Russian Federation)] [Moscow State University (Russian Federation); Makarova, I. P. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)] [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Arpaia, R.; Gunnarsson, R.; Lombardi, F. [Chalmers University of Technology, Department of Microtechnology and Nanoscience (Sweden)] [Chalmers University of Technology, Department of Microtechnology and Nanoscience (Sweden)

2013-09-15

46

Thin Films Module  

NSDL National Science Digital Library

This page from Nano-Link contains the document required for the thin films module. The activity requires a background in eight grade science. This 9 page guide includes background information on thin film interference, a hands-on learning activity, links to multimedia resources, and further readings. Visitors must complete a quick and free registration to access the materials.

47

Active superconducting devices formed of thin films  

DOEpatents

Active superconducting devices are formed of thin films of superconductor which include a main conduction channel which has an active weak link region. The weak link region is composed of an array of links of thin film superconductor spaced from one another by voids and selected in size and thickness such that magnetic flux can propagate across the weak link region when it is superconducting. Magnetic flux applied to the weak link region will propagate across the array of links causing localized loss of superconductivity in the links and changing the effective resistance across the links. The magnetic flux can be applied from a control line formed of a superconducting film deposited coplanar with the main conduction channel and weak link region on a substrate. The devices can be formed of any type to superconductor but are particularly well suited to the high temperature superconductors since the devices can be entirely formed from coplanar films with no overlying regions. The devices can be utilized for a variety of electrical components, including switching circuits, amplifiers, oscillators and modulators, and are well suited to microwave frequency applications.

Martens, Jon S. (Madison, WI); Beyer, James B. (Madison, WI); Nordman, James E. (Madison, WI); Hohenwarter, Gert K. G. (Madison, WI)

1991-05-28

48

Magnetite thin films  

Microsoft Academic Search

A low temperature process for converting hematite (?-Fe2O3) thin films into magnetite (Fe3O4is described. The films produced are unambiguously identified as magnetite by several complementary methods of analysis. These include ?-backscattering spectrography, X-ray powder diffractometry, and observations of electrical, magnetic, and optical properties.

J. Feng; C. Bajorek; M.-A. Nicolet

1972-01-01

49

Thermionic vacuum arc (TVA) technique for magnesium thin film deposition  

NASA Astrophysics Data System (ADS)

In this study, magnesium thin films were deposited on glass substrate by the Thermionic Vacuum Arc (TVA) technique for the first time. We present a different technique for deposition of high-quality magnesium thin films. By means of this technique, the production of films is achieved by condensing the plasma of anode material generated using Thermionic Vacuum Arc (TVA) under high vacuum conditions onto the surface to be coated. The crystal orientation and morphology of the deposited films were investigated by using XRD, EDX, SEM and AFM. The aim of this study is to search the use of TVA technique to coat magnesium thin films and to determine some of the physical properties of the films generated. Furthermore, this study will contribute to the scientific studies which search the thin films of magnesium or the compounds containing magnesium. In future, this study will be preliminary work to entirely produce magnesium diboride (MgB 2) superconductor thin film with the TVA technique.

Balbag, M. Z.; Pat, S.; Ozkan, M.; Ekem, N.; Musa, G.

2010-08-01

50

Thin film photovoltaics  

SciTech Connect

Thin films are considered a potentially attractive technological approach to making cost-effective electricity by photovoltaics. Over the last twenty years, many have been investigated and some (cadmium telluride, copper indium diselenide, amorphous silicon) have become leading candidates for future large-scale commercialization. This paper surveys the past development of these key thin films and gives their status and future prospects. In all cases, significant progress toward cost-effective PV electricity has been made. If this progress continues, it appears that thin film PV could provide electricity that is competitive for summer daytime peaking power requirements by the middle of the 1990s; and electricity in a range that is competitive with fossil fuel costs (i.e., 6 cents/kilowatt-hour) should be available from PV around the turn of the century. 22 refs., 9 figs.

Zweibel, K.; Ullal, H.S.

1989-05-01

51

Thin film temperature sensor  

NASA Technical Reports Server (NTRS)

Thin film surface temperature sensors were developed. The sensors were made of platinum-platinum/10 percent rhodium thermocouples with associated thin film-to-lead wire connections and sputtered on aluminum oxide coated simulated turbine blades for testing. Tests included exposure to vibration, low velocity hydrocarbon hot gas flow to 1250 K, and furnace calibrations. Thermal electromotive force was typically two percent below standard type S thermocouples. Mean time to failure was 42 hours at a hot gas flow temperature of 1250 K and an average of 15 cycles to room temperature. Failures were mainly due to separation of the platinum thin film from the aluminum oxide surface. Several techniques to improve the adhesion of the platinum are discussed.

Grant, H. P.; Przybyszewski, J. S.

1980-01-01

52

Thin film ceramic thermocouples  

NASA Technical Reports Server (NTRS)

A thin film ceramic thermocouple (10) having two ceramic thermocouple (12, 14) that are in contact with each other in at least on point to form a junction, and wherein each element was prepared in a different oxygen/nitrogen/argon plasma. Since each element is prepared under different plasma conditions, they have different electrical conductivity and different charge carrier concentration. The thin film thermocouple (10) can be transparent. A versatile ceramic sensor system having an RTD heat flux sensor can be combined with a thermocouple and a strain sensor to yield a multifunctional ceramic sensor array. The transparent ceramic temperature sensor that could ultimately be used for calibration of optical sensors.

Gregory, Otto (Inventor); Fralick, Gustave (Inventor); Wrbanek, John (Inventor); You, Tao (Inventor)

2011-01-01

53

Thin film photovoltaic device  

DOEpatents

A thin film photovoltaic solar cell which utilizes a zinc phosphide semiconductor is of the homojunction type comprising an n-type conductivity region forming an electrical junction with a p-type region, both regions consisting essentially of the same semiconductor material. The n-type region is formed by treating zinc phosphide with an extrinsic dopant such as magnesium. The semiconductor is formed on a multilayer substrate which acts as an opaque contact. Various transparent contacts may be used, including a thin metal film of the same chemical composition as the n-type dopant or conductive oxides or metal grids.

Catalano, Anthony W. (Wilmington, DE); Bhushan, Manjul (Wilmington, DE)

1982-01-01

54

Thin film photovoltaic device  

DOEpatents

A thin film photovoltaic solar cell which utilizes a zinc phosphide semiconductor is of the homojunction type comprising an n-type conductivity region forming an electrical junction with a p-type region, both regions consisting essentially of the same semiconductor material. The n-type region is formed by treating zinc phosphide with an extrinsic dopant such as magnesium. The semiconductor is formed on a multilayer substrate which acts as an opaque contact. Various transparent contacts may be used, including a thin metal film of the same chemical composition as the n-type dopant or conductive oxides or metal grids. 5 figs.

Catalano, A.W.; Bhushan, M.

1982-08-03

55

Vertically Aligned Nanocomposite Thin Films  

E-print Network

Vertically aligned nanocomposite (VAN) thin films have recently stimulated significant research interest to achieve better material functionality or multifunctionalities. In VAN thin films, both phases grow epitaxially in parallel on given...

Bi, Zhenxing

2012-07-16

56

Thin film solar cell workshop  

NASA Technical Reports Server (NTRS)

A summation of responses to questions posed to the thin-film solar cell workshop and the ensuing discussion is provided. Participants in the workshop included photovoltaic manufacturers (both thin film and crystalline), cell performance investigators, and consumers.

Armstrong, Joe; Jeffrey, Frank

1993-01-01

57

NMR characterization of thin films  

DOEpatents

A method, apparatus, and system for characterizing thin film materials. The method, apparatus, and system includes a container for receiving a starting material, applying a gravitational force, a magnetic force, and an electric force or combinations thereof to at least the starting material, forming a thin film material, sensing an NMR signal from the thin film material and analyzing the NMR signal to characterize the thin film of material.

Gerald, II, Rex E. (Brookfield, IL); Klingler, Robert J. (Glenview, IL); Rathke, Jerome W. (Homer Glen, IL); Diaz, Rocio (Chicago, IL); Vukovic, Lela (Westchester, IL)

2008-11-25

58

Thin film photovoltaic cell  

DOEpatents

A thin film photovoltaic cell having a transparent electrical contact and an opaque electrical contact with a pair of semiconductors therebetween includes utilizing one of the electrical contacts as a substrate and wherein the inner surface thereof is modified by microroughening while being macro-planar.

Meakin, John D. (Newark, DE); Bragagnolo, Julio (Newark, DE)

1982-01-01

59

Electrochromic thin films  

Microsoft Academic Search

An electrochromic material has the property of changing color when voltage is applied across it. It is possible electronically to alter a window's transmission and reflection properties by use of electrochromic thin films. This allows regulation of conductive and radiative heat transfer rates, with variable optical attenuation in the visible and infrared part of the solar radiation. Suitable materials for

C. Nyman; U. Gullenberg; M. Leppihalme

1987-01-01

60

Evaluation of motion of a high- Tc superconducting thin film in microgravity experiments  

NASA Astrophysics Data System (ADS)

Motion of a high- Tc superconducting (HTS) thin film was observed in microgravity experiments with a free fall drop shaft facility. The field-cooled thin film was suspended under a permanent magnet in the free fall experiments. When the magnet was rotated in microgravity, the thin film moved to a stable position where centrifugal force was balanced to restoring force caused by pinning of superconductor. The motion of the HTS thin film is numerically evaluated by using the frozen field model, which is based on an assumption that fluxoids are fixed at pinning points on the surface of the superconductor. The numerical evaluation is useful to explain the experimental results.

Tsuchimoto, Masanori; Matsuura, Kikyotaka; Homma, Norio; Matsuda, Mizushi

1999-08-01

61

Fullerene thin films  

SciTech Connect

The authors have been involved in the production of the purified fullerenes C{sub 60} and C{sub 70}. Previous research into fullerene thin films has been limited to mixtures of C{sub 60} and C{sub 70}. They plan to characterize high-purity C{sub 60} and C{sub 70} films in terms of photoconductivity, electrical conductivity, and optical absorption. They hope to do their studies with samples of purities better than 99% and 85% for C{sub 60} and C{sub 70}, respectively. Present work concerns the construction of an evaporation/deposition chamber. At this meeting, they hope to have grown and begun characterization of thin films on insulating and metallic substrates both with and without an additional metallic layer in {open_quotes}sandwich{close_quotes} structure.

Coram, G.J.; Castle, J.C.; Halas, N.J.

1992-12-01

62

Thin-film photovoltaics  

NASA Astrophysics Data System (ADS)

CdTe and CuIn1-xGaxSe2-ySy (CIGSS) are ideal candidates for thin-film solar cells. Present photovoltaic (PV) conversion efficiencies of champion thin-film solar cells are: CuIn1-xGaxSe2 (CIGS) 19.5%, CdTe 16.5%, and a-Si:H 12.4%. Thin-film PV modules could spearhead production growth of photovoltaics in the United States because of their added production capacity. For this purpose, module efficiencies must be improved to the 13%-15% range. Obtaining Ohmic contacts is difficult, especially for CdTe, because of the inherently low p-type doping level. Therefore, increasing the p-type doping level is important. Growth of CIGSS film must be controlled carefully as it transitions from Cu-rich to In-rich composition. Other issues for CIGSS cells are minimizing indium consumption, and increasing process throughput of selenization/sulfurization and transparent conducting oxide deposition. Development of all-dry processing for CdS deposition would be beneficial for both cells. This paper discusses basic devices and related issues.

Dhere, Neelkanth G.; Dhere, Ramesh G.

2005-07-01

63

Advanced thin film thermocouples  

NASA Technical Reports Server (NTRS)

The fabrication, materials characterization, and performance of thin film platinum rhodium thermocouples on gas turbine alloys was investigated. The materials chosen for the study were the turbine blade alloy systems MAR M200+Hf with NiCoCrAlY and FeCrAlY coatings, and vane alloy systems MAR M509 with FeCrAlY. Research was focussed on making improvements in the problem areas of coating substrate stability, adhesion, and insulation reliability and durability. Diffusion profiles between the substrate and coating with and without barrier coatings of Al2O3 are reported. The relationships between fabrication parameters of thermal oxidation and sputtering of the insulator and its characterization and performance are described. The best thin film thermocouples were fabricated with the NiCoCrAlY coatings which were thermally oxidized and sputter coated with Al2O3.

Kreider, K. G.; Semancik, S.; Olson, C.

1984-01-01

64

thin films as absorber  

NASA Astrophysics Data System (ADS)

Photovoltaic structures were prepared using AgSb(S x Se1- x )2 as absorber and CdS as window layer at various conditions via a hybrid technique of chemical bath deposition and thermal evaporation followed by heat treatments. Silver antimony sulfo selenide thin films [AgSb(S x Se1- x )2] were prepared by heating multilayers of sequentially deposited Sb2S3/Ag dipped in Na2SeSO3 solution, glass/Sb2S3/Ag/Se. For this, Sb2S3 thin films were deposited from a chemical bath containing SbCl3 and Na2S2O3. Then, Ag thin films were thermally evaporated on glass/Sb2S3, followed by selenization by dipping in an acidic solution of Na2SeSO3. The duration of dipping was varied as 3, 4 and 5 h. Two different heat treatments, one at 350 °C for 20 min in vacuum followed by a post-heat treatment at 325 °C for 2 h in Ar, and the other at 350 °C for 1 h in Ar, were applied to the multilayers of different configurations. X-ray diffraction results showed the formation of AgSb(S x Se1- x )2 thin films as the primary phase and AgSb(S,Se)2 and Sb2S3 as secondary phases. Morphology and elemental detection were done by scanning electron microscopy and energy dispersive X-ray analysis. X-ray photoelectron spectroscopic studies showed the depthwise composition of the films. Optical properties were determined by UV-vis-IR transmittance and reflection spectral analysis. AgSb(S x Se1- x )2 formed at different conditions was incorporated in PV structures glass/FTO/CdS/AgSb(S x Se1- x )2/C/Ag. Chemically deposited post-annealed CdS thin films of various thicknesses were used as window layer. J- V characteristics of the cells were measured under dark and AM1.5 illumination. Analysis of the J- V characteristics resulted in the best solar cell parameters of V oc = 520 mV, J sc = 9.70 mA cm-2, FF = 0.50 and ? = 2.7 %.

González, J. O.; Shaji, S.; Avellaneda, D.; Castillo, G. A.; Das Roy, T. K.; Krishnan, B.

2014-09-01

65

Thin film composite electrolyte  

DOEpatents

The invention is a thin film composite solid (and a means for making such) suitable for use as an electrolyte, having a first layer of a dense, non-porous conductive material; a second layer of a porous ionic conductive material; and a third layer of a dense non-porous conductive material, wherein the second layer has a Coefficient of thermal expansion within 5% of the coefficient of thermal expansion of the first and third layers.

Schucker, Robert C. (The Woodlands, TX)

2007-08-14

66

Thin Film Optical Coatings  

NASA Astrophysics Data System (ADS)

Within the scientific conception of the modern world, thin film optical coatings can be interpreted as one-dimensional photonic crystals. In general, they are composed of a sequence of single layers which consist of different transparent dielectrics with a thickness in the nanometer scale according to the operation wavelength range. The major function of these photonic structures is to adapt the properties of an optical surface to the needs of specific applications. By application of optical thin film coatings with optimized designs, the spectral characteristics of a surface can be modified to practically any required transfer function for a certain wavelength range. For example, the Fresnel reflection of a lens or a laser window can be suppressed for a broad wavelength range by depositing an antireflective coating containing only a few single layers. On the basis of a layer stack with alternating high- and low-refracting materials, high reflectance values up to 99.999% can be achieved for a certain laser wavelength. In addition to these basic functions, optical coatings can realize a broad variety of spectral filter characteristics according to even extremely sophisticated demands in modern precision optics and laser technology. Moreover, recent developments in optical thin film technology provide the means to combine selected optical properties with other features concerning, for instance, the thermal, mechanical or chemical stability of a surface. The latest progress in ophthalmic coatings even includes the integration of self-cleaning, photoactive or anti-fogging functions in antireflective coatings on glass.

Ristau, Detlev; Ehlers, Henrik

67

Enhanced Superconducting Properties of Iron Chalcogenide Thin Films  

E-print Network

. Compared with its bulk counterpart, iron-based superconductor thin film has a great potential in developing the ordered quasi-2D structure and is suitable for coating technology which has already been applied in YBa_2Cu_3O_7-x coated conductors...

Chen, Li

2013-07-26

68

Polycrystalline thin film photovoltaic technology  

SciTech Connect

Low-cost, high-efficiency thin-film modules are an exciting photovoltaic technology option for generating cost-effective electricity in 1995 and beyond. In this paper we review the significant technical progress made in the following thin films: copper indium diselenide, cadmium telluride, and polycrystalline thin silicon films. Also, the recent US DOE/SERI initiative to commercialize these emerging technologies is discussed. 6 refs., 9 figs.

Ullal, H.S.; Zweibel, K.; Mitchell, R.L.; Noufi, R.

1991-03-01

69

Nonlinear optical thin films  

NASA Technical Reports Server (NTRS)

A focused approach to development and evaluation of organic polymer films for use in optoelectronics is presented. The issues and challenges that are addressed include: (1) material synthesis, purification, and the tailoring of the material properties; (2) deposition of uniform thin films by a variety of methods; (3) characterization of material physical properties (thermal, electrical, optical, and electro-optical); and (4) device fabrication and testing. Photonic materials, devices, and systems were identified as critical technology areas by the Department of Commerce and the Department of Defense. This approach offers strong integration of basic material issues through engineering applications by the development of materials that can be exploited as the active unit in a variety of polymeric thin film devices. Improved materials were developed with unprecedented purity and stability. The absorptive properties can be tailored and controlled to provide significant improvement in propagation losses and nonlinear performance. Furthermore, the materials were incorporated into polymers that are highly compatible with fabrication and patterning processes for integrated optical devices and circuits. By simultaneously addressing the issues of materials development and characterization, keeping device design and fabrication in mind, many obstacles were overcome for implementation of these polymeric materials and devices into systems. We intend to considerably improve the upper use temperature, poling stability, and compatibility with silicon based devices. The principal device application that was targeted is a linear electro-optic modulation etalon. Organic polymers need to be properly designed and coupled with existing integrated circuit technology to create new photonic devices for optical communication, image processing, other laser applications such as harmonic generation, and eventually optical computing. The progression from microscopic sample to a suitable film-forming material in a working device is a complex, multifaceted endeavor. It requires close attention to maintaining the optical properties of the electro-optic active portion of the polymer while manipulating the polymer structure to obtain the desired secondary polymer properties.

Leslie, Thomas M.

1993-01-01

70

Brittle Thin Films Andrea Braides Irene Fonseca  

E-print Network

for brittle thin films is obtained from a 3-dime* *nsional fracture model for elastic material. -convergence Brittle Thin Films Andrea Braides Irene Fonseca Words : -limit, thin films, functions of bounded variation, fracture mecha* *nics Introduction

71

Thin film ion conducting coating  

DOEpatents

Durable thin film ion conducting coatings are formed on a transparent glass substrate by the controlled deposition of the mixed oxides of lithium:tantalum or lithium:niobium. The coatings provide durable ion transport sources for thin film solid state storage batteries and electrochromic energy conservation devices.

Goldner, Ronald B. (Lexington, MA); Haas, Terry (Sudbury, MA); Wong, Kwok-Keung (Watertown, MA); Seward, George (Arlington, MA)

1989-01-01

72

Thin films: Past, present, future  

SciTech Connect

This report describes the characteristics of the thin film photovoltaic modules necessary for an acceptable rate of return for rural areas and underdeveloped countries. The topics of the paper include a development of goals of cost and performance for an acceptable PV system, a review of current technologies for meeting these goals, issues and opportunities in thin film technologies.

Zweibel, K.

1995-04-01

73

Magnetochromatic thin-film microplates.  

PubMed

A new type of magnetochromatic material is developed based on thin-film interference of microplates self-assembled from super-paramagnetic nanocrystals. Dynamic optical tuning can be achieved through orientational manipulation of free-standing super-paramagnetic thin-film microplates using external magnetic fields. PMID:25408459

He, Le; Janner, Michael; Lu, Qipeng; Wang, Mingsheng; Ma, Hua; Yin, Yadong

2015-01-01

74

Transport properties at the insulator-superconductor phase boundary of La 2- xSr xCuO 4 thin films  

NASA Astrophysics Data System (ADS)

The longitudinal resistivity and the transverse Hall resistivity of La 1.94Sr 0.06CuO 4 and La 1.97Sr 0.03CuO 4 epitaxial thin films are investigated. The zero-field resistivity ?( T) of La 1.94Sr 0.06CuO 4 shows a minimum at 80 K and a resistive midpoint of the superconducting transition at Tcmid?7.5 K. A magnetic field of 8 T suppresses the superconducting state and induces a semiconducting normal state with ?( T) increasing with decreasing temperature. The resistivity of La 1.97Sr 0.03CuO 4 has a minimum at 100 K and no superconducting transition is observed down to 1.5 K. The semiconducting low-temperature behaviour can be described by Shlovskii-Efros hopping, while the metallic-like regime corresponds to 1D quantum transport of charge stripes. The field dependence of the Hall resistivity ? xy( B) has an opposite behaviour for the two doping levels: the ? xy( B) slope of La 1.94Sr 0.06CuO 4 decreases with decreasing temperature, while it increases in the case of La 1.97Sr 0.03CuO 4. Within the superconducting transition regime of La 1.94Sr 0.06CuO 4 (below 15 K) we observe a sign inversion of ? xy( B) in the limit of weak magnetic fields.

Wagner, P.; Ruan, K.-Q.; Gordon, I.; Vanacken, J.; Moshchalkov, V. V.; Bruynseraede, Y.

2001-07-01

75

Ferromagnetic thin films  

DOEpatents

A ferromagnetic [delta]-Mn[sub 1[minus]x]Ga[sub x] thin film having perpendicular anisotropy is described which comprises: (a) a GaAs substrate, (b) a layer of undoped GaAs overlying said substrate and bonded thereto having a thickness ranging from about 50 to about 100 nanometers, (c) a layer of [delta]-Mn[sub 1[minus]x]Ga[sub x] overlying said layer of undoped GaAs and bonded thereto having a thickness ranging from about 20 to about 30 nanometers, and (d) a layer of GaAs overlying said layer of [delta]-Mn[sub 1[minus]x]Ga[sub x] and bonded thereto having a thickness ranging from about 2 to about 5 nanometers, wherein x is 0.4[+-]0.05. 7 figures.

Krishnan, K.M.

1994-12-20

76

Polyimide Aerogel Thin Films  

NASA Technical Reports Server (NTRS)

Polyimide aerogels have been crosslinked through multifunctional amines. This invention builds on "Polyimide Aerogels With Three-Dimensional Cross-Linked Structure," and may be considered as a continuation of that invention, which results in a polyimide aerogel with a flexible, formable form. Gels formed from polyamic acid solutions, end-capped with anhydrides, and cross-linked with the multifunctional amines, are chemically imidized and dried using supercritical CO2 extraction to give aerogels having density around 0.1 to 0.3 g/cubic cm. The aerogels are 80 to 95% porous, and have high surface areas (200 to 600 sq m/g) and low thermal conductivity (as low as 14 mW/m-K at room temperature). Notably, the cross-linked polyimide aerogels have higher modulus than polymer-reinforced silica aerogels of similar density, and can be fabricated as both monoliths and thin films.

Meador, Mary Ann; Guo, Haiquan

2012-01-01

77

Ferromagnetic thin films  

DOEpatents

A ferromagnetic .delta.-Mn.sub.1-x Ga.sub.x thin film having perpendicular anisotropy is described which comprises: (a) a GaAs substrate, (b) a layer of undoped GaAs overlying said substrate and bonded thereto having a thickness ranging from about 50 to about 100 nanometers, (c) a layer of .delta.-Mn.sub.1-x Ga.sub.x overlying said layer of undoped GaAs and bonded thereto having a thickness ranging from about 20 to about 30 nanometers, and (d) a layer of GaAs overlying said layer of .delta.-Mn.sub.1-x Ga.sub.x and bonded thereto having a thickness ranging from about 2 to about 5 nanometers, wherein x is 0.4 .+-.0.05.

Krishnan, Kannan M. (Berkeley, CA)

1994-01-01

78

Superconducting properties of iron chalcogenide thin films  

NASA Astrophysics Data System (ADS)

Iron chalcogenides, binary FeSe, FeTe and ternary FeTexSe1-x, FeTexS1-x and FeTe:Ox, are the simplest compounds amongst the recently discovered iron-based superconductors. Thin films of iron chalcogenides present many attractive features that are covered in this review, such as: (i) easy fabrication and epitaxial growth on common single-crystal substrates; (ii) strong enhancement of superconducting transition temperature with respect to the bulk parent compounds (in FeTe0.5Se0.5, zero-resistance transition temperature Tc0bulk = 13.5 K, but Tc0film = 19 K on LaAlO3 substrate); (iii) high critical current density (Jc ˜ 0.5 ×106 A cm2 at 4.2 K and 0 T for FeTe0.5Se0.5 film deposited on CaF2, and similar values on flexible metallic substrates (Hastelloy tapes buffered by ion-beam assisted deposition) with a weak dependence on magnetic field; (iv) high upper critical field (˜50 T for FeTe0.5Se0.5, Bc2(0), with a low anisotropy, ? ˜ 2). These highlights explain why thin films of iron chalcogenides have been widely studied in recent years and are considered as promising materials for applications requiring high magnetic fields (20-50 T) and low temperatures (2-10 K).

Mele, Paolo

2012-10-01

79

Fabrication of high-quality superconductor-insulator-superconductor junctions on thin SiN membranes  

NASA Technical Reports Server (NTRS)

We have successfully fabricated high-quality and high-current density superconductor-insulator-superconductor (SIS) junctions on freestanding thin silicon nitride (SIN) membranes. These devices can be used in a novel millimeter-wave and THz receiver system which is made using micromachining. The SIS junctions with planar antennas were fabricated first on a silicon wafer covered with a SiN membrane, the Si wafer underneath was then etched away using an anisotropic KOH etchant. The current-voltage characteristics of the SIS junctions remained unchanged after the whole process, and the junctions and the membrane survived thermal cycling.

Garcia, Edouard; Jacobson, Brian R.; Hu, Qing

1993-01-01

80

Photoconductivity in Mesostructured Thin Films  

Microsoft Academic Search

Mesostructured silica films are widely studied due to their different structures, properties and variety of possible applications. Sodium dodecyl sulfate (SDS)-templated sol-gel silica films possess highly ordered lamellar phase structure. It is expected that molecules and polymer chains line up with these layered structures when incorporated into the films. Mesostructured thin films were doped with Dispersed Red 1 (DR1) and

G Valverde; J. García Macedo; Daniel Cruz; J. I. Zink; R. Hernández

2003-01-01

81

Spontaneous vortices in ferromagnet-superconductor systems  

E-print Network

We study the interaction between superconductors and ferromagnets in two systems: a ferromagnet-superconductor bilayer, and a thin superconducting film with a periodic array of magnetic dots upon it, with spontaneous vortices appearing...

Wei, Hongduo

2006-08-16

82

Thin film cell development workshop report  

NASA Technical Reports Server (NTRS)

The Thin Film Development Workshop provided an opportunity for those interested in space applications of thin film cells to debate several topics. The unique characteristics of thin film cells as well as a number of other issues were covered during the discussions. The potential of thin film cells, key research and development issues, manufacturing issues, radiation damage, substrates, and space qualification of thin film cells were discussed.

Woodyard, James R.

1991-01-01

83

Mechanical properties of thin films  

Microsoft Academic Search

The mechanical properties of thin films on substrates are described and studied. It is shown that very large stresses may\\u000a be present in the thin films that comprise integrated circuits and magnetic disks and that these stresses can cause deformation\\u000a and fracture to occur. It is argued that the approaches that have proven useful in the study of bulk structural

William D. Nix

1989-01-01

84

MgB 2 superconducting thin films on Si and Al 2O 3 substrates  

Microsoft Academic Search

Thin films of the superconductor MgB2 were prepared by three different procedures on sapphire and silicon substrates. Boron thin films, ex situ annealed in magnesium vapour, resulted in textured polycrystalline films with crystal dimensions below about 1 ?m, onset critical temperature Tcon near 39 K and width of phase transition ?T?1 K. Both, ex situ and in situ annealed co-deposited

A. Plecenik; L. Satrapinsky; P. Kús; Š Gaži; Š Be?a?ka; I. Vavra; I. Kostic

2001-01-01

85

Effect of microstructure on thermal conductivity of Cu, Ag thin films.  

PubMed

Thin film type materials are widely used in modern industries, such as semiconductor devices, functional superconductors, machining tools, and so on. The thermal properties of material in semiconductor are very important factors for stable operation because the heat generated during device operation may increase clock frequency. Even though thermal properties of thin films may play a major role in assessing reliability of parts, the measurement methods of thin film thermal properties are generally known to be complex to devise. In this study, a temperature distribution method was applied for the measurement of thermal conductivity of Cu and Ag thin film on borosilicate glass substrate. Cu and Ag thin films were deposited on borosilicate glass using thermal evaporation processes. To measure the thermal conductivity changes according to the microstructure of metallic thin film, the processing variables for the Cu and Ag thin film deposition were changed. To minimize the effect of film thickness, the film thickness was fixed to the thickness of approximately 500 nm throughout experiments. The thermal conductivities of thin films were measured to be much lower than those of bulk materials. Thin film with larger grain size showed higher thermal conductivity probably due to the lower number density of grain boundary. Weidman-Franz law could be applied to thin films produced in this study. Thermal conductivity was also estimated from the resistivity of thin film and Lorenz number of bulk material. PMID:20358967

Ryu, Sang; Juhng, Woonam; Kim, Youngman

2010-05-01

86

Thin-Film Power Transformers  

NASA Technical Reports Server (NTRS)

Transformer core made of thin layers of insulating material interspersed with thin layers of ferromagnetic material. Flux-linking conductors made of thinner nonferromagnetic-conductor/insulator multilayers wrapped around core. Transformers have geometric features finer than those of transformers made in customary way by machining and mechanical pressing. In addition, some thin-film materials exhibit magnetic-flux-carrying capabilities superior to those of customary bulk transformer materials. Suitable for low-cost, high-yield mass production.

Katti, Romney R.

1995-01-01

87

Photoconductivity of thin organic films  

Microsoft Academic Search

Thin organic films were deposited on silicon oxide surfaces with golden interdigitated electrodes (interelectrode gap was 2?m), and the film resistivities were measured in dark and under white light illumination. The compounds selected for the measurements include molecules widely used in solar cell applications, such as polythiophene (PHT), fullerene (C60), pyrelene tetracarboxylic diimide (PTCDI) and copper phthalocyanine (CuPc), as well

Nikolai V. Tkachenko; Vladimir Chukharev; Petra Kaplas; Antti Tolkki; Alexander Efimov; Kimmo Haring; Jukka Viheriälä; Tapio Niemi; Helge Lemmetyinen

2010-01-01

88

Nanotemplated lead telluride thin films  

Microsoft Academic Search

Direct lyotropic liquid crystalline templating has been successfully applied to produce nanostructured IV–VI semiconductor PbTe thin films by electrodeposition both on gold and n-type (100) silicon substrates. The PbTe films were characterized by transmission electron microscopy, X-ray diffraction and polarized optical microscopy and the results show that the films have a regular hexagonal nanoarchitecture with a high crystalline rock salt

Xiaohong Li; Iris S. Nandhakumar; George S. Attard; Matthew L. Markham; David C. Smith; Jeremy J. Baumberg

2009-01-01

89

Simple vortex states in films of type-I Ginzburg-Landau superconductor  

NASA Astrophysics Data System (ADS)

Sufficiently thin films of type-I superconductor in a perpendicular magnetic field exhibit a triangular vortex lattice while thick films develop an intermediate state. To elucidate what happens between these two regimes, precise numerical calculations have been made within Ginzburg-Landau theory at ?=0.5 and 0.25 for a variety of vortex lattice structures with one flux quantum per unit cell. The phase diagram in the space of mean induction and film thickness includes a narrow wedge in which a square lattice is stable, surrounded by the domain of stability of the triangular lattice at thinner films/lower fields and, on the other side, rectangular lattices with continuously varying aspect ratio. The vortex lattice has an anomalously small shear modulus within and close to the square lattice phase. Solutions of the Ginzburg-Landau equations have been obtained by similar calculations for bulk systems and thin films with one vortex but two flux quanta per square or triangular unit cell. Primitive lattices of double-fluxoid vortices are thermodynamically unstable in bulk in both type-I and type-II superconductors, as expected. In type-I films these double-fluxoid lattices do not pre-empt the single-fluxoid lattice structures.

Sweeney, Mark C.; Gelfand, Martin P.

2010-12-01

90

Epitaxial antiperovskite superconducting CuNNi3 thin films synthesized by chemical solution deposition.  

PubMed

Epitaxial antiperovskite superconducting CuNNi3 thin films have been grown by chemical solution deposition. The film is a type II superconductor and shows a Tc of 3.2 K with a transition of 0.13 K. The Hc2(0) and ?0 are estimated to be 8.1 kOe and 201 Å, respectively. PMID:25197779

Hui, Zhenzhen; Tang, Xianwu; Shao, Dingfu; Lei, Hechang; Yang, Jie; Song, Wenhai; Luo, Hongmei; Zhu, Xuebin; Sun, Yuping

2014-10-28

91

The Thin Oil Film Equation  

NASA Technical Reports Server (NTRS)

A thin film of oil on a surface responds primarily to the wall shear stress generated on that surface by a three-dimensional flow. The oil film is also subject to wall pressure gradients, surface tension effects and gravity. The partial differential equation governing the oil film flow is shown to be related to Burgers' equation. Analytical and numerical methods for solving the thin oil film equation are presented. A direct numerical solver is developed where the wall shear stress variation on the surface is known and which solves for the oil film thickness spatial and time variation on the surface. An inverse numerical solver is also developed where the oil film thickness spatial variation over the surface at two discrete times is known and which solves for the wall shear stress variation over the test surface. A One-Time-Level inverse solver is also demonstrated. The inverse numerical solver provides a mathematically rigorous basis for an improved form of a wall shear stress instrument suitable for application to complex three-dimensional flows. To demonstrate the complexity of flows for which these oil film methods are now suitable, extensive examination is accomplished for these analytical and numerical methods as applied to a thin oil film in the vicinity of a three-dimensional saddle of separation.

Brown, James L.; Naughton, Jonathan W.

1999-01-01

92

Epitaxial gadolinium nitride thin films  

SciTech Connect

GdN thin films are deposited on MgO(100) by low-energy ion-beam-assisted molecular-beam epitaxy at elevated temperatures. Elemental analysis by secondary-ion mass spectrometry proves that a protective layer is imperative to avoid oxidation of the GdN films in air. In situ surface structural investigation of the growing GdN films by reflection high-energy electron diffraction reveals epitaxial film growth. This result is confirmed by x-ray diffraction structure and texture analysis. Accordingly, the GdN films on MgO(100) exhibit cube-on-cube epitaxy. Due to the epitaxial growth the crystalline quality of the films is by far higher than that of films previously reported of in literature.

Gerlach, J. W.; Mennig, J.; Rauschenbach, B. [Leibniz-Institut fuer Oberflaechenmodifizierung (IOM), Permoserstrasse 15, D-04318 Leipzig (Germany)

2007-02-05

93

Thin-film metal hydrides.  

PubMed

The goal of the medieval alchemist, the chemical transformation of common metals into nobel metals, will forever be a dream. However, key characteristics of metals, such as their electronic band structure and, consequently, their electric, magnetic and optical properties, can be tailored by controlled hydrogen doping. Due to their morphology and well-defined geometry with flat, coplanar surfaces/interfaces, novel phenomena may be observed in thin films. Prominent examples are the eye-catching hydrogen switchable mirror effect, the visualization of solid-state diffusion and the formation of complex surface morphologies. Thin films do not suffer as much from embrittlement and/or decrepitation as bulk materials, allowing the study of cyclic absorption and desorption. Therefore, thin-metal hydride films are used as model systems to study metal-insulator transitions, for high throughput combinatorial research or they may be used as indicator layers to study hydrogen diffusion. They can be found in technological applications as hydrogen sensors, in electrochromic and thermochromic devices. In this review, we discuss the effect of hydrogen loading of thin niobium and yttrium films as archetypical examples of a transition metal and a rare earth metal, respectively. Our focus thereby lies on the hydrogen induced changes of the electronic structure and the morphology of the thin films, their optical properties, the visualization and the control of hydrogen diffusion and on the study of surface phenomena and catalysis. PMID:18980236

Remhof, Arndt; Borgschulte, Andreas

2008-12-01

94

Beryllium thin films for resistor applications  

NASA Technical Reports Server (NTRS)

Beryllium thin films have a protective oxidation resistant property at high temperature and high recrystallization temperature. However, the experimental film has very low temperature coefficient of resistance.

Fiet, O.

1972-01-01

95

Thin-film forces in pseudoemulsion films  

SciTech Connect

Use of foam for enhanced oil recovery (EOR) has shown recent success in steam-flooding field applications. Foam can also provide an effective barrier against gas coning in thin oil zones. Both of these applications stem from the unique mobility-control properties a stable foam possesses when it exists in porous media. Unfortunately, oil has a major destabilizing effect on foam. Therefore, it is important for EOR applications to understand how oil destroys foam. Studies all indicate that stabilization of the pseudoemulsion film is critical to maintain foam stability in the presence of oil. Hence, to aid in design of surfactant formulations for foam insensitivity to oil the authors pursue direct measurement of the thin-film or disjoining forces that stabilize pseudoemulsion films. Experimental procedures and preliminary results are described.

Bergeron, V.; Radke, C.J. [California Univ., Berkeley, CA (United States). Dept. of Chemical Engineering]|[Lawrence Berkeley Lab., CA (United States)

1991-06-01

96

Thin films under chemical stress  

SciTech Connect

The goal of work on this project has been develop a set of experimental tools to allow investigators interested in transport, binding, and segregation phenomena in composite thin film structures to study these phenomena in situ. Work to-date has focuses on combining novel spatially-directed optical excitation phenomena, e.g. waveguide eigenmodes in thin dielectric slabs, surface plasmon excitations at metal-dielectric interfaces, with standard spectroscopies to understand dynamic processes in thin films and at interfaces. There have been two main scientific thrusts in the work and an additional technical project. In one thrust we have sought to develop experimental tools which will allow us to understand the chemical and physical changes which take place when thin polymer films are placed under chemical stress. In principle this stress may occur because the film is being swelled by a penetrant entrained in solvent, because interfacial reactions are occurring at one or more boundaries within the film structure, or because some component of the film is responding to an external stimulus (e.g. pH, temperature, electric field, or radiation). However all work to-date has focused on obtaining a clearer understanding penetrant transport phenomena. The other thrust has addressed the kinetics of adsorption of model n-alkanoic acids from organic solvents. Both of these thrusts are important within the context of our long-term goal of understanding the behavior of composite structures, composed of thin organic polymer films interspersed with Langmuir-Blodgett (LB) and self-assembled monolayers. In addition there has been a good deal of work to develop the local technical capability to fabricate grating couplers for optical waveguide excitation. This work, which is subsidiary to the main scientific goals of the project, has been successfully completed and will be detailed as well. 41 refs., 10 figs.

Not Available

1991-01-01

97

Photooxidation and Photoconductivity of Polyferrocenylsilane Thin Films  

E-print Network

Photooxidation and Photoconductivity of Polyferrocenylsilane Thin Films Paul W. Cyr,1,2 Marian from the initial oxidation of Full Paper: Irradiation of thin films of poly.sargent@utoronto.ca Keywords: conducting polymers; inorganic polymers; photochemistry; photoconductivity Introduction Intense

98

Semiconductor-nanocrystal/conjugated polymer thin films  

SciTech Connect

The invention described herein provides for thin films and methods of making comprising inorganic semiconductor-nanocrystals dispersed in semiconducting-polymers in high loading amounts. The invention also describes photovoltaic devices incorporating the thin films.

Alivisatos, A. Paul; Dittmer, Janke J.; Huynh, Wendy U.; Milliron, Delia

2014-06-17

99

Semiconductor-nanocrystal/conjugated polymer thin films  

DOEpatents

The invention described herein provides for thin films and methods of making comprising inorganic semiconductor-nanocrystals dispersed in semiconducting-polymers in high loading amounts. The invention also describes photovoltaic devices incorporating the thin films.

Alivisatos, A. Paul (Oakland, CA); Dittmer, Janke J. (Munich, DE); Huynh, Wendy U. (Munich, DE); Milliron, Delia (Berkeley, CA)

2010-08-17

100

Nanomechanical properties of hydrated organic thin films  

E-print Network

Hydrated organic thin films are biological or synthetic molecularly thin coatings which impart a particular functionality to an underlying substrate and which have discrete water molecules associated with them. Such films ...

Choi, Jae Hyeok

2007-01-01

101

Semiconducting Polymers for Thin?Film Electronics  

Microsoft Academic Search

An overview of practical issues related to the adoption of semiconducting polymers in thin?film electronic devices is presented. Performance requirements for organic light emitting diodes, thin?film transistors and photovoltaic devices are reviewed.

Michael L. Chabinyc

2006-01-01

102

Thin film-coated polymer webs  

DOEpatents

The present invention relates to thin film-coated polymer webs, and more particularly to thin film electronic devices supported upon a polymer web, wherein the polymer web is treated with a purifying amount of electron beam radiation.

Wenz, Robert P. (Cottage Grove, MN); Weber, Michael F. (Shoreview, MN); Arudi, Ravindra L. (Woodbury, MN)

1992-02-04

103

Diamond Thin Films Handbook David S. Dandy  

E-print Network

1 Diamond Thin Films Handbook Chapter 4 David S. Dandy Department of Chemical Engineering Colorado Sandia National Laboratories Albuquerque, New Mexico 87185 To appear in Diamond Thin Films Handbook J...............................................................................................................................3 II. Gas-phase processes in CVD diamond

Dandy, David

104

Low work function, stable thin films  

DOEpatents

Generation of low work function, stable compound thin films by laser ablation. Compound thin films with low work function can be synthesized by simultaneously laser ablating silicon, for example, and thermal evaporating an alkali metal into an oxygen environment. For example, the compound thin film may be composed of Si/Cs/O. The work functions of the thin films can be varied by changing the silicon/alkali metal/oxygen ratio. Low work functions of the compound thin films deposited on silicon substrates were confirmed by ultraviolet photoelectron spectroscopy (UPS). The compound thin films are stable up to 500.degree. C. as measured by x-ray photoelectron spectroscopy (XPS). Tests have established that for certain chemical compositions and annealing temperatures of the compound thin films, negative electron affinity (NEA) was detected. The low work function, stable compound thin films can be utilized in solar cells, field emission flat panel displays, electron guns, and cold cathode electron guns.

Dinh, Long N. (Concord, CA); McLean, II, William (Oakland, CA); Balooch, Mehdi (Berkeley, CA); Fehring, Jr., Edward J. (Dublin, CA); Schildbach, Marcus A. (Livermore, CA)

2000-01-01

105

Microwave response of high transition temperature superconducting thin films  

NASA Technical Reports Server (NTRS)

We have studied the microwave response of YBa2Cu3O(7 - delta), Bi-Sr-Ca-Cu-O, and Tl-Ba-Ca-Cu-O high transition temperature superconducting (HTS) thin films by performing power transmission measurements. These measurements were carried out in the temperature range of 300 K to 20 K and at frequencies within the range of 30 to 40 GHz. Through these measurements we have determined the magnetic penetration depth (lambda), the complex conductivity (sigma(sup *) = sigma(sub 1) - j sigma(sub 2)) and the surface resistance (R(sub s)). An estimate of the intrinsic penetration depth (lambda approx. 121 nm) for the YBa2Cu3O(7 - delta) HTS has been obtained from the film thickness dependence of lambda. This value compares favorably with the best values reported so far (approx. 140 nm) in single crystals and high quality c-axis oriented thin films. Furthermore, it was observed that our technique is sensitive to the intrinsic anisotropy of lambda in this superconductor. Values of lambda are also reported for Bi-based and Tl-based thin films. We observed that for the three types of superconductors, both sigma(sub 1) and sigma(sub 2) increased when cooling the films below their transition temperature. The measured R(sub s) are in good agreement with other R(sub S) values obtained using resonant activity techniques if we assume a quadratic frequency dependence. Our analysis shows that, of the three types of HTS films studied, the YBa2Cu3O(7 - delta) thin film, deposited by laser ablation and off-axis magnetron sputtering are the most promising for microwave applications.

Miranda, Felix Antonio

1991-01-01

106

Effects of post-annealing on the infrared active phonon modes of low anisotropy ( ?=5-11) Cu 1- xTl xBa 2Ca 2Cu 3O 10- ? superconductor thin films  

NASA Astrophysics Data System (ADS)

The effects of post-annealing conditions on the apical oxygen phonon modes have been investigated and their correlations with the critical temperature of the Cu 1- xTl xBa 2Ca 2Cu 3O 10- ? (Cu 1- xTl x-1223) superconductor thin films have been developed. The samples were annealed in different ambient environments, such as air, N 2, O 2 and vacuum and their FTIR absorption spectrum has been taken. Three absorption peaks observed between 455-440, 665-648 and 1240-1246 cm -1 are assigned to apical oxygen vibrations, the chain axis O(3) vibrations and to C-O single-bond, respectively. The frequency of the mode at 655 cm -1 is sensitive to the concentration of O(3) in the charge reservoir layer, which in turn controls increase or decrease of the bond length of apical oxygen. The softening of the apical oxygen mode is possibly linked with the reduction of thallium, which in turn is associated with the amount of oxygen [O(3)] in the charge reservoir layer. In as-prepared material and annealed under oxygen, the state of thallium is not reduced from Tl +3 to Tl +1 and sufficient number of carriers are not supplied to CuO 2 planes, the material remains in the region of carrier under-doping. The softening of apical oxygen mode positioned at 455 cm -1 is associated with the formation of low Tc phases. The C-O related IR mode is softened with the post-annealing in air at 780 °C and annealing in N 2 ambient at 400 °C. The critical transition temperature is found to decrease with the post-annealing at 400 °C in N 2, which is possibly due to the under-doped CuO 2 planes of the material. However, the post-annealing at 780 and 650 °C increases Tc (mid-point) to 107 and 111 K respectively.

Khan, Nawazish A.; Khurram, A. A.; Mazhar, M.

2004-08-01

107

Disentanglement in thin polymer films  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulations of thin polymer films confined between structureless walls show accelerated in-plane dynamics with decreasing film thickness. Using the primitive path analysis (PPA) introduced by Everaers et al [Science 303 (2004) 823] for chain length up to N=1024, we can show that the entanglement density decreases with decreasing film thickness. However, the effect becomes pronounced only for films thinner than the bulk radius of gyration where also the chain structure becomes modified by the confinement [1]. The PPA algorithm can be modified to estimate the contribution of self-entanglements: The latter become more important for thinner films, however, they do not counterbalance the global decrease of entanglements. [1] H. Meyer et al Eur. Phys. J. Sp.Top. 141 (2007) 167.

Meyer, Hendrik

2008-03-01

108

Thin Film Piezoelectrics for MEMS  

Microsoft Academic Search

Thin film piezoelectric materials offer a number of advantages in microelectromechanical systems (MEMS), due to the large motions that can be generated, often with low hysteresis, the high available energy densities, as well as high sensitivity sensors with wide dynamic ranges, and low power requirements. This paper reviews the literature in this field, with an emphasis on the factors that

S. Trolier-McKinstry; P. Muralt

2004-01-01

109

Thin Film Solid Lubricant Development  

NASA Technical Reports Server (NTRS)

Tribological coatings for high temperature sliding applications are addressed. A sputter-deposited bilayer coating of gold and chromium is investigated as a potential solid lubricant for protection of alumina substrates during sliding at high temperature. Evaluation of the tribological properties of alumina pins sliding against thin sputtered gold films on alumina substrates is presented.

Benoy, Patricia A.

1997-01-01

110

Thin film polymeric gel electrolytes  

DOEpatents

Novel hybrid thin film electrolyte, based on an organonitrile solvent system, which are compositionally stable, environmentally safe, can be produced efficiently in large quantity and which, because of their high conductivities .apprxeq.10.sup.-3 .OMEGA..sup.-1 cm.sup.-1 are useful as electrolytes for rechargeable lithium batteries.

Derzon, Dora K. (1554 Rosalba St. NE., Albuquerque, Bernalillo County, NM 87112); Arnold, Jr., Charles (3436 Tahoe, NE., Albuquerque, Bernalillo County, NM 87111); Delnick, Frank M. (9700 Fleming Rd., Dexter, MI 48130)

1996-01-01

111

Thin film polymeric gel electrolytes  

DOEpatents

Novel hybrid thin film electrolytes, based on an organonitrile solvent system, which are compositionally stable, environmentally safe, can be produced efficiently in large quantity and which, because of their high conductivities {approx_equal}10{sup {minus}3}{Omega}{sup {minus}1} cm{sup {minus}1} are useful as electrolytes for rechargeable lithium batteries. 1 fig.

Derzon, D.K.; Arnold, C. Jr.; Delnick, F.M.

1996-12-31

112

Thin films and uses  

DOEpatents

The invention provides a method for synthesizing a titanium oxide-containing film comprising the following steps: (a) preparing an aqueous solution of a titanium chelate with a titanium molarity in the range of 0.01M to 0.6M. (b) immersing a substrate in the prepared solution, (c) decomposing the titanium chelate to deposit a film on the substrate. The titanium chelate maybe decomposed acid, base, temperature or other means. A preferred method provides for the deposit of adherent titanium oxide films from C2 to C5 hydroxy carboxylic acids. In another aspect the invention is a novel article of manufacture having a titanium coating which protects the substrate against ultraviolet damage. In another aspect the invention provides novel semipermeable gas separation membranes, and a method for producing them.

Baskaran, Suresh (Kennewick, WA); Graff, Gordon L. (Kennewick, WA); Song, Lin (Richland, WA)

1998-01-01

113

Superconducting and insulating phases of disordered FeSe thin films  

NASA Astrophysics Data System (ADS)

The temperature-dependent electronic transport on the superconducting and insulating sides of the superconductor-insulator transition in disordered quasi-two-dimensional textured FeSe thin films is reported. The transition is driven by gradually decreasing the thickness of individual films, thus increasing disorder. In the superconducting phase pronounced resistance tails evolve when the thickness decreases toward the critical thickness of the superconductor-insulator transition. The resistance tails are described reasonably well by the inverse Arrhenius law originally used to account for electronic transport in disordered granular thin films of conventional superconductors below the bulk transition temperature. The transport in the insulating phase is characterized by thermally activated variable range hopping.

Schneider, Rudolf; Zaitsev, Alexander G.; Fuchs, Dirk; v. Löhneysen, Hilbert

2015-01-01

114

Ohmic Contact To Amorphous Carbon Thin Films  

NASA Astrophysics Data System (ADS)

Amorphous carbon (a-C) thin films have been deposited on silicon substrates at different deposition temperatures ranging from 700° C-800° C. The objective of this work is to investigate several electrical contacts on a-C thin films and to find the suitable method to fabricate ohmic contact on a-C thin films that prepared from a natural product, camphor (C10H16O). The a-C thin films were prepared with a simple thermal CVD method. In this study, Aurum (Au) and Platinum (Pt) were selected as the metal contact to a-C thin films. I-V characteristics measurement was carried out to study the contact between metal and a-C thin films. It was found that increasing deposition temperature also contributes to the variation I-V characteristics of a-C thin films.

Mohamad, F.; Noor, U. M.; Rusop, M.

2009-06-01

115

Sputter deposition for multi-component thin films  

DOEpatents

Ion beam sputter-induced deposition using a single ion beam and a multicomponent target is capable of reproducibly producing thin films of arbitrary composition, including those which are close to stoichiometry. Using a quartz crystal deposition monitor and a computer controlled, well-focused ion beam, this sputter-deposition approach is capable of producing metal oxide superconductors and semiconductors of the superlattice type such as GaAs-AlGaAs as well as layered metal/oxide/semiconductor/superconductor structures. By programming the dwell time for each target according to the known sputtering yield and desired layer thickness for each material, it is possible to deposit composite films from a well-controlled sub-monolayer up to thicknesses determined only by the available deposition time. In one embodiment, an ion beam is sequentially directed via a set of X-Y electrostatic deflection plates onto three or more different element or compound targets which are constituents of the desired film. In another embodiment, the ion beam is directed through an aperture in the deposition plate and is displaced under computer control to provide a high degree of control over the deposited layer. In yet another embodiment, a single fixed ion beam is directed onto a plurality of sputter targets in a sequential manner where the targets are each moved in alignment with the beam under computer control in forming a multilayer thin film. This controlled sputter-deposition approach may also be used with laser and electron beams. 10 figs.

Krauss, A.R.; Auciello, O.

1990-05-08

116

Sputter deposition for multi-component thin films  

DOEpatents

Ion beam sputter-induced deposition using a single ion beam and a multicomponent target is capable of reproducibly producing thin films of arbitrary composition, including those which are close to stoichiometry. Using a quartz crystal deposition monitor and a computer controlled, well-focused ion beam, this sputter-deposition approach is capable of producing metal oxide superconductors and semiconductors of the superlattice type such as GaAs-AlGaAs as well as layered metal/oxide/semiconductor/superconductor structures. By programming the dwell time for each target according to the known sputtering yield and desired layer thickness for each material, it is possible to deposit composite films from a well-controlled sub-monolayer up to thicknesses determined only by the available deposition time. In one embodiment, an ion beam is sequentially directed via a set of X-Y electrostatic deflection plates onto three or more different element or compound targets which are constituents of the desired film. In another embodiment, the ion beam is directed through an aperture in the deposition plate and is displaced under computer control to provide a high degree of control over the deposited layer. In yet another embodiment, a single fixed ion beam is directed onto a plurality of sputter targets in a sequential manner where the targets are each moved in alignment with the beam under computer control in forming a multilayer thin film. This controlled sputter-deposition approach may also be used with laser and electron beams.

Krauss, Alan R. (Plainfield, IL); Auciello, Orlando (Cary, NC)

1990-01-01

117

Thin Films Using Al Doping  

NASA Astrophysics Data System (ADS)

We have studied the influence of Al doping on the microstructural, optical, and electrical properties of spray-deposited WO3 thin films. XRD analyses confirm that all the films are of polycrystalline WO3 in nature, possessing monoclinic structure. EDX profiles of the Al-doped films show aluminum peaks implying incorporation of Al ions into WO3 lattice. On Al doping, the average crystallite size decreases due to increase in the density of nucleation centers at the time of film growth. The observed variation in the lattice parameter values on Al doping is attributed to the incorporation of Al ions into WO3 lattice. Enhancement in the direct optical band gap compared to the undoped film has been observed on Al doping due to decrease in the width of allowed energy states near the conduction band edge. The refractive indices of the films follow the Cauchy relation of normal dispersion. Electrical resistivity compared to the undoped film has been found to increase on Al doping.

Mukherjee, Ramnayan; Prajapati, C. S.; Sahay, P. P.

2014-09-01

118

Sputtered thin film research  

Microsoft Academic Search

The reactive RF sputtering technique was applied to the preparation of a wide variety of materials. Single crystal films of ZnO, TiO2, WO3 AlN and GaN were grown on one or more of the insulating crystalline substrates of Al2O3, MgAl2O3, SiC and LiNbO3. Data on the deposition parameters, structure and optical waveguiding characteristics of the heteroepitaxial structures are presented. Reactive

A. J. Shuskus; D. J. Quinn; E. L. Paradis; J. M. Berak; D. E. Cullen

1974-01-01

119

Modeling of multilayer thin film recording media  

Microsoft Academic Search

A previously developed micromagnetic model for single-layer thin-film recording media is extended to model multilayer thin-film media. Effects of the magnetostatic interactions between the adjacent magnetic layers in the film are studied for a film with two magnetic layers separated by an ideal nonmagnetic layer. Magnetization reversal processes and hysteresis properties are studied for films with different separation layer thicknesses.

Jian-Gang Zhu

1992-01-01

120

Substrate Dependence of Structural and Transport Properties in FeSe0.5Te0.5 Thin Films  

Microsoft Academic Search

In order to clarify the best condition for the growth of iron chalcogenide superconductor thin films, we investigated the effect of the substrate on the transport and structural properties of films. Thin films of FeSe0.5Te0.5 grown by pulsed laser deposition were characterized by DC electrical resistivity, Hall effect, X-ray diffraction measurements, and transmission electron microscopy (TEM) observation. The c-axis length

Masafumi Hanawa; Ataru Ichinose; Seiki Komiya; Ichiro Tsukada; Takanori Akiike; Yoshinori Imai; Tatsuo Hikage; Takahiko Kawaguchi; Hiroshi Ikuta; Atsutaka Maeda

2011-01-01

121

Photoconductivity of thin organic films  

NASA Astrophysics Data System (ADS)

Thin organic films were deposited on silicon oxide surfaces with golden interdigitated electrodes (interelectrode gap was 2 ?m), and the film resistivities were measured in dark and under white light illumination. The compounds selected for the measurements include molecules widely used in solar cell applications, such as polythiophene ( PHT), fullerene ( C60), pyrelene tetracarboxylic diimide ( PTCDI) and copper phthalocyanine ( CuPc), as well as molecules potentially interesting for photovoltaic applications, e.g. porphyrin-fullerene dyads. The films were deposited using thermal evaporation (e.g. for C60 and CuPc films), spin coating for PHT, and Langmuir-Schaeffer for the layer-by-layer deposition of porphyrin-fullerene dyads. The most conducting materials in the series are films of PHT and CuPc with resistivities 1.2 × 10 3 ? m and 3 × 10 4 ? m, respectively. Under light illumination resistivity of all films decreases, with the strongest light effect observed for PTCDI, for which resistivity decreases by 100 times, from 3.2 × 10 8 ? m in dark to 3.1 × 10 6 ? m under the light.

Tkachenko, Nikolai V.; Chukharev, Vladimir; Kaplas, Petra; Tolkki, Antti; Efimov, Alexander; Haring, Kimmo; Viheriälä, Jukka; Niemi, Tapio; Lemmetyinen, Helge

2010-04-01

122

Thin-Film Selective Emitter  

NASA Technical Reports Server (NTRS)

Direct conversion of thermal energy into electrical energy using a photovoltaic cell is called thermophotovoltaic energy conversion. One way to make this an efficient process is to have the thermal energy source be an efficient selective emitter of radiation. The emission must be near the band-gap energy of the photovoltaic cell. One possible method to achieve an efficient selective emitter is the use of a thin film of rare-earth oxides. The determination of the efficiency of such an emitter requires analysis of the spectral emittance of the thin film including scattering and reflectance at the vacuum-film and film-substrate interfaces. Emitter efficiencies (power emitted in emission band/total emitted power) in the range 0.35-0.7 are predicted. There is an optimum optical depth to obtain maximum efficiency. High emitter efficiencies are attained only for low (less than 0.05) substrate emittance values, both with and without scattering. The low substrate emittance required for high efficiency limits the choice of substrate materials to highly reflective metals or high-transmission materials such as sapphire.

Chubb, Donald L.; Lowe, Roland A.

1993-01-01

123

Field distribution in thin superconductors with secondary peak in magnetisation  

NASA Astrophysics Data System (ADS)

The high- Tc superconductors show non-monotonic dependence of the critical current density Jc on the magnetic field B which manifests in the magnetisation curves as a peak at intermediate fields (`fish-tail' effect). The field distribution in the non-monotonic region is simulated by exploiting the analogy of a two dimensional inductive Josephson junction array to that of a hard type-II superconductor in an applied magnetic field. The simulation is carried out for demagnetisation factor N=0 and N>0.9, corresponding to the case of an infinite slab parallel to and a thin sample transverse to an applied field, respectively. We observe that the increase in Jc( B) at an intermediate field is accommodated by a change in the sign of the curvature of the field profile. This gives a point of inflexion where the slope of the screening current also changes sign. For N?1, the peak-effect region in Jc( B) is experienced even for small applied fields due to large field induced at the edge.

Chandran, Mahesh

1998-08-01

124

Preparation of thin ceramic films via an aqueous solution route  

DOEpatents

A new chemical method of forming thin ceramic films has been developed. An aqueous solution of metal nitrates or other soluble metal salts and a low molecular weight amino acid is coated onto a substrate and pyrolyzed. The amino acid serves to prevent precipitation of individual solution components, forming a very viscous, glass-like material as excess water is evaporated. Using metal nitrates and glycine, the method has been demonstrated for zirconia with various levels of yttria stabilization, for lanthanum-strontium chromites, and for yttrium-barium-copper oxide superconductors on various substrates.

Pederson, Larry R. (Kennewick, WA); Chick, Lawrence A. (Richland, WA); Exarhos, Gregory J. (Richland, WA)

1989-01-01

125

Local stress in thin polystyrene films  

NASA Astrophysics Data System (ADS)

Thin polymer films have received significant attention due to the deviation of material properties from bulk values. Part of the difficulty in describing the underlying physics is an incomplete understanding of how internal and surface stresses affect thin films. Here we exploit ``wrinkling'' to create a simple model system in which local stress can be easily tuned. When a thin polymer film bound to an elastic substrate is subjected to a compressive stress the film buckles out of plane. Due to the curvature at each crest and trough of the wrinkles, there arise local stresses in the polymer film. The curvature of the wrinkles is controlled by the modulus of the film and substrate, the film thickness and the applied stress, allowing us to apply an arbitrary local stress. After wrinkling, films are annealed above their glass transition temperature which allows flow and relaxes any stress. The local stress is then transferred to that of a thickness variation in the thin film. Importantly the flow of thin polymer films can be modeled using the well established lubrication theory, resulting in a simple scaling model. Our model allows us to investigate the response of thin films where deviations from bulk behavior are expected, as well as more complex thin diblock polymer films.

Gurmessa, Bekele; Croll, Andrew

2012-02-01

126

Zinc oxide thin film acoustic sensor  

NASA Astrophysics Data System (ADS)

This paper reports the implementation of (750 nm) thickness of Zinc Oxide (ZnO) thin film for the piezoelectric pressure sensors. The film was prepared and deposited employing the spray pyrolysis technique. XRD results show that the growth preferred orientation is the (002) plane. A polycrystalline thin film (close to mono crystallite like) was obtained. Depending on the Scanning Electron Microscopy photogram, the film homogeneity and thickness were shown. The resonance frequency measured (about 19 kHz) and the damping coefficient was calculated and its value was found to be about (2.5538), the thin film be haves as homogeneous for under and over damped. The thin film pressure sensing was approximately exponentially related with frequency, the thin film was observed to has a good response for mechanical stresses also it is a good material for the piezoelectric properties.

Mohammed, Ali Jasim; Salih, Wafaa Mahdi; Hassan, Marwa Abdul Muhsien; Mansour, Hazim Louis; Nusseif, Asmaa Deiaa; Kadhum, Haider Abdullah

2013-12-01

127

Zinc oxide thin film acoustic sensor  

SciTech Connect

This paper reports the implementation of (750 nm) thickness of Zinc Oxide (ZnO) thin film for the piezoelectric pressure sensors. The film was prepared and deposited employing the spray pyrolysis technique. XRD results show that the growth preferred orientation is the (002) plane. A polycrystalline thin film (close to mono crystallite like) was obtained. Depending on the Scanning Electron Microscopy photogram, the film homogeneity and thickness were shown. The resonance frequency measured (about 19 kHz) and the damping coefficient was calculated and its value was found to be about (2.5538), the thin film be haves as homogeneous for under and over damped. The thin film pressure sensing was approximately exponentially related with frequency, the thin film was observed to has a good response for mechanical stresses also it is a good material for the piezoelectric properties.

Mohammed, Ali Jasim; Salih, Wafaa Mahdi; Hassan, Marwa Abdul Muhsien; Nusseif, Asmaa Deiaa; Kadhum, Haider Abdullah [Department of Physics , College of Science, Al-Mustansiriyah University, Baghdad (Iraq); Mansour, Hazim Louis [Department of Physics , College of Education, Al-Mustansiriyah University, Baghdad (Iraq)

2013-12-16

128

Atomic layer deposition of thin superconducting films and multilayers  

NASA Astrophysics Data System (ADS)

We report the use of atomic layer deposition (ALD) to synthesize thin superconducting films and multilayer superconductor-insulator (S-I) heterostructures including: nitrides, carbides, and silicides, nitrides of molybdenum and titanium, and Nb1-xTixN/AlN-based S-I heterostructures. The atomic-scale thickness control afforded by ALD enables the study of superconductivity and associated phenomena in homogeneous layers in the ultra-thin film limit. Two-dimensional superconductivity in such films is of interest from a fundamental point of view, as a new effect has recently been discovered at ultra-low temperature in thin superconducting films made by ALD: the super-insulating transition. Furthermore, the ALD technique applied to superconducting films opens the way for a variety of applications, including improving the performance and decreasing the cost of high energy particle accelerators, superconducting wires for energy storage, and bolometers for radiation detection. In this respect, we will present results on the ALD growth processes, the metallurgy and superconducting properties of these coatings.

Proslier, Thomas; Klug, Jeffrey; Groll, Nikolas; Altin, Serdar; Becker, Nicholas

2012-02-01

129

A thin film nitinol heart valve.  

PubMed

In order to create a less thrombogenic heart valve with improved longevity, a prosthetic heart valve was developed using thin film nitinol (NiTi). A "butterfly" valve was constructed using a single, elliptical piece of thin film NiTi and a scaffold made from Teflon tubing and NiTi wire. Flow tests and pressure readings across the valve were performed in vitro in a pulsatile flow loop. Bio-corrosion experiments were conducted on untreated and passivated thin film nitinol. To determine the material's in vivo biocompatibility, thin film nitinol was implanted in pigs using stents covered with thin film NiTi. Flow rates and pressure tracings across the valve were comparable to those through a commercially available 19 mm Perimount Edwards tissue valve. No signs of corrosion were present on thin film nitinol samples after immersion in Hank's solution for one month. Finally, organ and tissue samples explanted from four pigs at 2, 3, 4, and 6 weeks after thin film NiTi implantation appeared without disease, and the thin film nitinol itself was without thrombus formation. Although long term testing is still necessary, thin film NiTi may be very well suited for use in artificial heart valves. PMID:16438227

Stepan, Lenka L; Levi, Daniel S; Carman, Gregory P

2005-11-01

130

Direct deposition of magnetite thin films on organic semiconductors  

NASA Astrophysics Data System (ADS)

Technological procedures able to produce high quality electrodes from magnetic oxides in vertical organic-inorganic hybrid devices is a challenging task in the field of organic spintronics. Thin films of magnetite (Fe3O4) have been successfully grown directly on top of organic semiconductor layers, tris(8-hydroxyquinoline)aluminium(III) (Alq3), by pulsed-electron ablation technique. The films show ferromagnetic behavior and good structural quality, properties detected by magneto-optical Kerr effect, superconductor quantum interference device, micro-Raman spectroscopy, and Atomic Force Microscopy. The ferromagnetic behavior persists even for 10nm thick films. Charge injection at magnetite-organic interface has been finally demonstrated by detecting electroluminescence from Alq3.

Arisi, Emilia; Bergenti, Ilaria; Cavallini, Massimiliano; Riminucci, Alberto; Ruani, Giampiero; Dediu, Valentin; Ghidini, Massimo; Pernechele, Chiara; Solzi, Massimo

2008-09-01

131

Superconductors  

NSDL National Science Digital Library

Superconductors.org, a non-profit, non-affiliated Website, provides this clear introduction to the world of superconductors. Starting appropriately with Heike Kamerlingh Onnes, the first man to observe superconductivity in 1911, a history of superconductors section familiarizes students and laymen with the development of materials that have no resistance to the flow of electricity. Subsequent sections include uses for superconductors, various types of superconductors, links to current superconductor news, and patents.

Eck, Joe

2003-10-10

132

Morphological stability of thin films  

SciTech Connect

The boundary element method for elastostatics is applied to a thin stability problem arising in solid state surface science. An aim of this work is to determine the morphology of Ge deposited on a Si substrate. Nonstandard boundary conditions at the material interface are used to model the epitaxially grown film. In addition to determining the deformed geometry, it is also necessary to compute the surface stress tensor. Although the surface displacement at the junction between the interface and the Si free surface is not differentiable, the hypersingular integral equation for surface stress can still be used. These techniques are described along with results from 2-D calculations.

Gray, L.J.; Chisholm, M.F.; Kaplan, T.

1993-12-31

133

Thin film solar energy collector  

DOEpatents

A multi-layer solar energy collector of improved stability comprising: (1) a substrate of quartz, silicate glass, stainless steel or aluminum-containing ferritic alloy; (2) a solar absorptive layer comprising silver, copper oxide, rhodium/rhodium oxide and 0-15% by weight of platinum; (3) an interlayer comprising silver or silver/platinum; and (4) an optional external anti-reflective coating, plus a method for preparing a thermally stable multi-layered solar collector, in which the absorptive layer is undercoated with a thin film of silver or silver/platinum to obtain an improved conductor-dielectric tandem.

Aykan, Kamran (Monmouth Beach, NJ); Farrauto, Robert J. (Westfield, NJ); Jefferson, Clinton F. (Millburn, NJ); Lanam, Richard D. (Westfield, NJ)

1983-11-22

134

A geometric model for coarsening during spiral-mode growth of thin films  

Microsoft Academic Search

We study the coarsening observed in spiral-mode growth of thin films. The high-temperature superconductor YBa 2Cu3O7 provides a suitable model system. The density of spirals at the surface decreases as the film gets thicker. In other words, the grain size coarsens with distance from the substrate. We propose a simple mechanism for this coarsening, based on geometrical competition of spirals

T. P. Schulze; R. V. Kohn

1999-01-01

135

Comparison of fluctuation effects in layered HTSC and thin films of LTSC  

NASA Astrophysics Data System (ADS)

The resistive properties of layered HTSC in the mixed state are compared with those of thin films of conventional superconductors with weak and strong disorder. It is shown that the transition into the Abrikosov state is smooth both in the layered HTSC and the LTSC films. The obtained results show that the amount of pinning disorders, rather than a difference between HTSC and LTSC, is the key factor ruling fluctuation influence on the resistive properties.

Nikulov, Alexey V.; Balestrino, Giuseppe; Milani, Enrico; Oboznov, Vladimir A.

2000-07-01

136

Electro-deposition of superconductor oxide films  

DOEpatents

Methods for preparing high quality superconducting oxide precursors which are well suited for further oxidation and annealing to form superconducting oxide films. The method comprises forming a multilayered superconducting precursor on a substrate by providing an electrodeposition bath comprising an electrolyte medium and a substrate electrode, and providing to the bath a plurality of precursor metal salts which are capable of exhibiting superconducting properties upon subsequent treatment. The superconducting precursor is then formed by electrodepositing a first electrodeposited (ED) layer onto the substrate electrode, followed by depositing a layer of silver onto the first electrodeposited (ED) layer, and then electrodepositing a second electrodeposited (ED) layer onto the Ag layer. The multilayered superconducting precursor is suitable for oxidation at a sufficient annealing temperature in air or an oxygen-containing atmosphere to form a crystalline superconducting oxide film.

Bhattacharya, Raghu N. (Littleton, CO)

2001-01-01

137

Electrostatic thin film chemical and biological sensor  

DOEpatents

A chemical and biological agent sensor includes an electrostatic thin film supported by a substrate. The film includes an electrostatic charged surface to attract predetermined biological and chemical agents of interest. A charge collector associated with said electrostatic thin film collects charge associated with surface defects in the electrostatic film induced by the predetermined biological and chemical agents of interest. A preferred sensing system includes a charge based deep level transient spectroscopy system to read out charges from the film and match responses to data sets regarding the agents of interest. A method for sensing biological and chemical agents includes providing a thin sensing film having a predetermined electrostatic charge. The film is exposed to an environment suspected of containing the biological and chemical agents. Quantum surface effects on the film are measured. Biological and/or chemical agents can be detected, identified and quantified based on the measured quantum surface effects.

Prelas, Mark A. (Columbia, MO); Ghosh, Tushar K. (Columbia, MO); Tompson, Jr., Robert V. (Columbia, MO); Viswanath, Dabir (Columbia, MO); Loyalka, Sudarshan K. (Columbia, MO)

2010-01-19

138

Magnetic Properties of Materials and Thin Films  

SciTech Connect

Magnetic and electromagnetic properties of materials and thin films are used extensively. Applications include actuators, storage devices, memory devices, EMI shielding devices, smart sensors, and motors. Magnetism basics must first be understood before the magnetic properties of thin films can be discussed.

Martin, Peter M.

2005-03-15

139

Thin films of mixed metal compounds  

DOEpatents

A compositionally uniform thin film of a mixed metal compound is formed by simultaneously evaporating a first metal compound and a second metal compound from independent sources. The mean free path between the vapor particles is reduced by a gas and the mixed vapors are deposited uniformly. The invention finds particular utility in forming thin film heterojunction solar cells.

Mickelsen, Reid A. (Bellevue, WA); Chen, Wen S. (Seattle, WA)

1985-01-01

140

Thermal conductivity of dielectric thin films  

Microsoft Academic Search

A direct reading thermal comparator has been used to measure the thermal conductivity of dielectric thin film coatings. In the past, the thermal comparator has been used extensively to measure the thermal conductivity of bulk solids, liquids, and gases. The technique has been extended to thin film materials by making experimental improvements and by the application of an analytical heat

J. C. Lambropoulos; M. R. Jolly; C. A. Amaden; S. E. Gilman; M. J. Sinicropi; D. Diakomihalis; S. D. Jacobs

1989-01-01

141

Cellulose triacetate, thin film dielectric capacitor  

NASA Technical Reports Server (NTRS)

Very thin films of cellulose triacetate are cast from a solution containing a small amount of high boiling temperature, non-solvent which evaporates last and lifts the film from the casting surface. Stretched, oriented, crystallized films have high electrical breakdown properties. Metallized films less than about 2 microns in thickness form self-healing electrodes for high energy density, pulsed power capacitors. Thicker films can be utilized as a dielectric for a capacitor.

Yen, Shiao-Ping S. (inventor); Jow, T. Richard (inventor)

1995-01-01

142

Cellulose triacetate, thin film dielectric capacitor  

NASA Technical Reports Server (NTRS)

Very thin films of cellulose triacetate are cast from a solution containing a small amount of high boiling temperature, non-solvent which evaporates last and lifts the film from the casting surface. Stretched, oriented, crystallized films have high electrical breakdown properties. Metallized films less than about 2 microns in thickness form self-healing electrodes for high energy density, pulsed power capacitors. Thicker films can be utilized as a dielectric for a capacitor.

Yen, Shiao-Ping S. (inventor); Jow, T. Richard (inventor)

1993-01-01

143

Electric breakdown of thin liquid films  

NASA Astrophysics Data System (ADS)

An experimental technique is developed for assessing stability of thin liquid films by application of electrical forces and simultaneous measurement of the electric conductivity of the system. The concept involves creating a thin film at the intersection of two micro-channels etched onto a glass substrate. Once a thin film is created, a ramped DC potential difference can be applied across it. The electrical stresses developed at the film interfaces lead to its rupture above a threshold potential. The potential at which the film ruptures is used to assess the stability of the film. Small channel dimensions in this microfluidic platform allow characterization of thin films formed between micron-sized droplets at high capillary pressures, which is difficult to attain using conventional thin film characterization techniques. The results of DC potential breakdown of films show that critical potential can be considered as a measure of thin film stability. Stability measurements using this technique were in accord with Langmuir adsorption model. Furthermore, impedance spectroscopy is used to measure capacitance of the films formed using the developed microfluidic device. The capacitance measurements led to the estimation of the film area which is unknown in the microfluidic device to the vantage point along the surface of the film. The effect of drainage time and adsorption time of films is studied using impedance spectroscopy. Similar to DC measurements, capacitance measurements of the film also suggested a Langmuir adsorption trend. Moreover, capacitance measurement of films under the effect of DC potential was conducted. The results showed a dependence of capacitance to square of applied DC potential.

Karimi Mostowfi, Farshid

144

A monolithic thin film electrochromic window  

SciTech Connect

Three closely related thin film solid state ionic devices that are potentially important for applications are: electrochromic smart windows, high energy density thin film rechargeable batteries, and thin film electrochemical sensors. Each usually has at least on mixed ion/electron conductor, an electron-blocking ion conductor, and an ion-blocking electron conductor, and many of the technical issues associated with thin film solid state ionics are common to all three devices. Since the electrochromic window has the added technical requirement of electrically-controlled optical modulation, (over the solar spectrum), and since research at the authors' institution has focused primarily on the window structure, this paper will address the electrochromic window, and particularly a monolithic variable reflectivity electrochromic window, as an illustrative example of some of the challenges and opportunities that are confronting the thin film solid state ionics community. 33 refs.

Goldner, R.B.; Arntz, F.O.; Berera, G.; Haas, T.E.; Wong, K.K. (Tufts Univ., Medford, MA (United States). Electro-Optics Technology Center); Wei, G. (Mobil Solar Energy Corp., Billerica, MA (United States)); Yu, P.C. (PPG Industries, Inc., Monroeville, PA (United States))

1991-01-01

145

A monolithic thin film electrochromic window  

SciTech Connect

Three closely related thin film solid state ionic devices that are potentially important for applications are: electrochromic smart windows, high energy density thin film rechargeable batteries, and thin film electrochemical sensors. Each usually has at least on mixed ion/electron conductor, an electron-blocking ion conductor, and an ion-blocking electron conductor, and many of the technical issues associated with thin film solid state ionics are common to all three devices. Since the electrochromic window has the added technical requirement of electrically-controlled optical modulation, (over the solar spectrum), and since research at the authors` institution has focused primarily on the window structure, this paper will address the electrochromic window, and particularly a monolithic variable reflectivity electrochromic window, as an illustrative example of some of the challenges and opportunities that are confronting the thin film solid state ionics community. 33 refs.

Goldner, R.B.; Arntz, F.O.; Berera, G.; Haas, T.E.; Wong, K.K. [Tufts Univ., Medford, MA (United States). Electro-Optics Technology Center; Wei, G. [Mobil Solar Energy Corp., Billerica, MA (United States); Yu, P.C. [PPG Industries, Inc., Monroeville, PA (United States)

1991-12-31

146

Magnetostrictive thin films for microwave spintronics  

PubMed Central

Multiferroic composite materials, consisting of coupled ferromagnetic and piezoelectric phases, are of great importance in the drive towards creating faster, smaller and more energy efficient devices for information and communications technologies. Such devices require thin ferromagnetic films with large magnetostriction and narrow microwave resonance linewidths. Both properties are often degraded, compared to bulk materials, due to structural imperfections and interface effects in the thin films. We report the development of epitaxial thin films of Galfenol (Fe81Ga19) with magnetostriction as large as the best reported values for bulk material. This allows the magnetic anisotropy and microwave resonant frequency to be tuned by voltage-induced strain, with a larger magnetoelectric response and a narrower linewidth than any previously reported Galfenol thin films. The combination of these properties make epitaxial thin films excellent candidates for developing tunable devices for magnetic information storage, processing and microwave communications. PMID:23860685

Parkes, D. E.; Shelford, L. R.; Wadley, P.; Holý, V.; Wang, M.; Hindmarch, A. T.; van der Laan, G.; Campion, R. P.; Edmonds, K. W.; Cavill, S. A.; Rushforth, A. W.

2013-01-01

147

Thin Dielectric Films Containing Tb3+ Ions For Application In Thin Film Solar Cells  

Microsoft Academic Search

Thin transparent dielectric films containing Tb3+ are developed for application as spectral converters of the solar spectrum in thin film silicon solar cells. The results on the deposition and characterization of thin SiO2 and Al2O3 films containing Tb3+ ions are presented. The films are prepared by RF magnetron co-sputtering, a well established technique for large area coatings. Photoluminescence (PL) is

M. Sendova-Vassileva; K. Baumgartner; O. Angelov; B. Holländer; D. Dimova-Malmovska; R. Carius

2010-01-01

148

Basic thin film processing for perovskite materials  

Microsoft Academic Search

Basic thin-film processing for ferroelectric perovskite oxides was investigated. Amorphous, polycrystal, and epitaxial thin films of Pb-based perovskite ferroelectrics were prepared by RF-magnetron sputtering and their properties are discussed. By utilizing the epitaxial PLZT films with excellent ferroelectric properties, several applications to optical electronic devices were examined, and an optical transmission system was constructed using high-speed PLZT optical switches. Trends

Hideaki Adachi; Makoto Kitabatake; Hidetaka Higashino; Kentaro Setsune; Kiyotaka Wasa

1990-01-01

149

Thin film limits for Ginzburg--Landau with strong applied magnetic fields  

E-print Network

In this work, we study thin-film limits of the full three-dimensional Ginzburg-Landau model for a superconductor in an applied magnetic field oriented obliquely to the film surface. We obtain Gamma-convergence results in several regimes, determined by the asymptotic ratio between the magnitude of the parallel applied magnetic field and the thickness of the film. Depending on the regime, we show that there may be a decrease in the density of Cooper pairs. We also show that in the case of variable thickness of the film, its geometry will affect the effective applied magnetic field, thus influencing the position of vortices.

Stan Alama; Lia Bronsard; Bernardo Galvão-Sousa

2009-06-30

150

Superconducting and Insulating Phases of Disordered FeSe Thin Films in a Magnetic Field  

NASA Astrophysics Data System (ADS)

The temperature-dependent electronic transport on the superconducting and insulating sides of the superconductor-insulator transition in disordered quasi-two-dimensional textured FeSe thin films is reported. The transition is driven by a perpendicular magnetic field applied to a film with its thickness close to the critical thickness of the thickness-, i.e., disorder-induced transition. The resistance in the superconducting phase might be dominated by thermally assisted flux flow, and in the phase diagram a metallic phase might intervene between the superconducting and insulating state at very low temperatures. In the insulating phase, weak insulating behavior is observed that can be described by weak localization theory of bosons, thus supporting the bosonic description of the superconductor-insulator transition in FeSe thin films.

Schneider, R.; Zaitsev, A. G.; Fuchs, D.; von Löhneysen, H.

2015-01-01

151

Defect formation in hafnium dioxide thin films.  

PubMed

Hafnium dioxide thin films were deposited by reactive electron-beam evaporation at six different substrate temperatures on fused-silica substrates. During the depositions, the scattering of light caused by the growth of defects in the films was recorded with in situ total internal reflection microscopy. After deposition the films were analyzed by angle-resolved scatterometery, spectrophotometric measurement of film reflectance and transmittance, atomic force microscopy, and x-ray diffraction. We explore the effects of film defect formation on film optical properties and film surface topography using these data. PMID:18345056

Reicher, D; Black, P; Jungling, K

2000-04-01

152

Nanotribology of confined thin films  

NASA Astrophysics Data System (ADS)

In this dissertation I present the results of the study of the friction behavior of molecularly smooth mica surfaces confining thin films of different materials. The main objective was to improve the basic understanding of the mechanism underlying frictional processes, to assist the development of new techniques of control and reduction of frictional waste and wear. The behavior of thin films of branched hydrocarbon lubricants under shear is described in detail. The evolution of the systems to steady-state sliding from rest or after a change in sliding velocity was thoroughly studied, and the presence of different length and time scales was observed. Using a new 'extended bimorph slider' which allows continuous shearing for distances well beyond the contact diameter (asperity size) I show that the evolution to steady-state sliding in these films is governed by the distance the surfaces are sheared rather than the time. From these results it is clear that both time and distance of sliding have to be considered in order to fully describe the dynamic response of lubricants and complex fluids under shear. The behavior of linear and branched hydrocarbon films under shear is compared, and the physical reasons for the different types of transitions and friction traces observed in the two systems are discussed. Two approaches to friction reduction were investigated. First, a new method for friction control and reduction is proposed. Using a Surface Forces Apparatus modified for measuring friction forces while simultaneously inducing normal (out-of-plane) vibrations between two sliding surfaces, load- and frequency-dependent transitions between a number of "dynamic friction" states are observed. In particular, regimes of vanishingly small friction at small interfacial oscillation amplitudes are found. Despite its complexity, the phenomenon is shown to have a molecular origin. Second, a novel lubricant material was studied in detail. The tribological behavior of colloidal particles of tungsten disulfide of different structures was studied using different techniques. Shear induced material transfer (via third body processes) from the colloidal particles to the surfaces was shown to be a dominant factor in the tribological behavior observed. Both platelet and nested spherical structures were investigated. An ultrathin, ordered layer with promising lubricative properties was observed when nested particles were sheared, while WS2 platelets produced a rough and disordered transfer layer, with substantially inferior lubricating properties.

Drummond, Carlos Alberto

153

Antimony sulfide thin films in chemically deposited thin film photovoltaic cells  

Microsoft Academic Search

Antimony sulfide thin films of thickness ?500 nm have been deposited on glass slides from chemical baths constituted with SbCl3 and sodium thiosulfate. Smooth specularly reflective thin films are obtained at deposition temperatures from ?3 to 10 °C. The differences in the film thickness and improvement in the crystallinity and photoconductivity upon annealing the film in nitrogen are presented. These films can

Sarah Messina; M. T. S. Nair; P. K. Nair

2007-01-01

154

Gas Permeation in Thin Glassy Polymer Films  

NASA Astrophysics Data System (ADS)

The development of asymmetric and composite membranes with very thin dense "skins" needed to achieve high gas fluxes enabled the commercial use of membranes for molecular level separations. It has been generally assumed that these thin skins, with thicknesses of the order of 100 nm, have the same permeation characteristics as films with thicknesses of 25 microns or more. Thick films are easily made in the laboratory and have been used extensively for measuring permeation characteristics to evaluate the potential of new polymers for membrane applications. There is now evidence that this assumption can be in very significant error, and use of thick film data to select membrane materials or predict performance should be done with caution. This presentation will summarize our work on preparing films of glassy polymers as thin as 20 nm and characterizing their behavior by gas permeation, ellipsometry and positron annihilation lifetime spectroscopy. Some of the most important polymers used commercially as gas separation membranes, i.e., Matrimid^ polyimide, polysulfone (PSF) and poly(2,6-dimethyl-1,4-phenylene oxide) (PPO), have been made into well-defined thin films in our laboratories by spin casting techniques and their properties studied using the techniques we have developed. These thin films densify (or physically age) much faster than thicker films, and, as result, the permeability decreases, sometimes by several-fold over weeks or months for thin films. This means that the properties of these thin films can be very different from bulk films. The techniques, interpretations and implications of these observations will be discussed. In a broader sense, gas permeation measurements can be a powerful way of developing a better understanding of the effects of polymer chain confinement and/or surface mobility on the behavior of thin films.

Paul, Donald

2011-03-01

155

Primary research efforts on exploring the commercial possibilities of thin film growth and materials purification in space  

NASA Technical Reports Server (NTRS)

The progress made on research programs in the 1987 to 1988 year is reported. The research is aimed at producing thin film semiconductors and superconductor materials in space. Sophisticated vacuum chambers and equipment were attained for the epitaxial thin film growth of semiconductors, metals and superconductors. In order to grow the best possible epitaxial films at the lowest possible temperatures on earth, materials are being isoelectronically doped during growth. It was found that isoelectrically doped film shows the highest mobility in comparison with films grown at optimal temperatures. Success was also attained in growing epitaxial films of InSb on sapphire which show promise for infrared sensitive devices in the III-V semiconductor system.

1989-01-01

156

Thin film bioreactors in space  

NASA Technical Reports Server (NTRS)

Studies from the Skylab, SL-3 and D-1 missions have demonstrated that biological organisms grown in microgravity have changes in basic cellular functions such as DNA, mRNA and protein synthesis, cytoskeleton synthesis, glucose utilization, and cellular differentiation. Since microgravity could affect prokaryotic and eukaryotic cells at a subcellular and molecular level, space offers an opportunity to learn more about basic biological systems with one inmportant variable removed. The thin film bioreactor will facilitate the handling of fluids in microgravity, under constant temperature and will allow multiple samples of cells to be grown with variable conditions. Studies on cell cultures grown in microgravity would make it possible to identify and quantify changes in basic biological function in microgravity which are needed to develop new applications of orbital research and future biotechnology.

Hughes-Fulford, M.; Scheld, H. W.

1989-01-01

157

VUV thin films, chapter 7  

NASA Technical Reports Server (NTRS)

The application of thin film technology to the vacuum ultraviolet (VUV) wavelength region from 120 nm to 230 nm has not been fully exploited in the past because of absorption effects which complicate the accurate determination of the optical functions of dielectric materials. The problem therefore reduces to that of determining the real and imaginary parts of a complex optical function, namely the frequency dependent refractive index n and extinction coefficient k. We discuss techniques for the inverse retrieval of n and k for dielectric materials at VUV wavelengths from measurements of their reflectance and transmittance. Suitable substrate and film materials are identified for application in the VUV. Such applications include coatings for the fabrication of narrow and broadband filters and beamsplitters. The availability of such devices open the VUV regime to high resolution photometry, interferometry and polarimetry both for space based and laboratory applications. This chapter deals with the optics of absorbing multilayers, the determination of the optical functions for several useful materials, and the design of VUV multilayer stacks as applied to the design of narrow and broadband reflection and transmission filters and beamsplitters. Experimental techniques are discussed briefly, and several examples of the optical functions derived for selected materials are presented.

Zukic, Muamer; Torr, Douglas G.

1993-01-01

158

Flexible thin metal film thermal sensing system  

NASA Technical Reports Server (NTRS)

A flexible thin metal film thermal sensing system is provided. A self-metallized polymeric film has a polymeric film region and a metal surface disposed thereon. A layer of electrically-conductive metal is deposited directly onto the self-metallized polymeric film's metal surface. Coupled to at least one of the metal surface and the layer of electrically-conductive metal is a device/system for measuring an electrical characteristic associated therewith as an indication of temperature.

Thomsen, Donald L. (Inventor)

2010-01-01

159

Thin-film rechargeable lithium batteries  

SciTech Connect

Small thin-film rechargeable cells have been fabricated with a lithium phosphorus oxyniuide electrolyte, Li metal anode, and Li{sub 1-x}Mn{sub 2}O{sub 4} as the cathode film. The cathode films were fabricated by several different techniques resulting in both crystalline and amorphous films. These were compared by observing the cell discharge behavior. Estimates have been made for the scale-up of such a thin-film battery to meet the specifications for the electric vehicle application. The specific energy, energy density, and cycle life are expected to meet the USABC mid-term criteria. However, the areas of the thin-films needed to fabricate such a cell are very large. The required areas could be greatly reduced by operating the battery at temperatures near 100{degrees}C or by enhancing the lithium ion transport rate in the cathode material.

Dudney, N.J.; Bates, J.B.; Lubben, D.

1994-11-01

160

Aging phenomena in polystyrene thin films  

E-print Network

The aging behavior is investigated for thin films of atactic polystyrene through measurements of complex electric capacitance. During isothermal aging process the real part of the electric capacitance increases with aging time, while the imaginary part decreases with aging time. This result suggests that the aging time dependence of the real and imaginary parts are mainly associated with change in thickness and dielectric permittivity, respectively. In thin films, the thickness depends on thermal history of aging even above the glass transition. Memory and `rejuvenation' effects are also observed in the thin films.

Koji Fukao; Hiroki Koizumi

2008-01-05

161

Permanent laser conditioning of thin film optical materials  

DOEpatents

The invention comprises a method for producing optical thin films with a high laser damage threshold and the resulting thin films. The laser damage threshold of the thin films is permanently increased by irradiating the thin films with a fluence below an unconditioned laser damage threshold.

Wolfe, C. Robert (Palo Alto, CA); Kozlowski, Mark R. (Pleasanton, CA); Campbell, John H. (Livermore, CA); Staggs, Michael (Tracy, CA); Rainer, Frank (Livermore, CA)

1995-01-01

162

Block copolymer directed nanoporous metal thin films.  

PubMed

Porous metal thin films have high potential for use in applications such as catalysis, electrical contacts, plasmonics, as well as energy storage and conversion. Structuring metal thin films on the nanoscale to generate high surface areas poses an interesting challenge as metals have high surface energy. In this communication, we demonstrate direct access to nanostructured metal nanoparticle hybrid thin films with high nanoparticle loadings through spin coating of a mixture of block copolymer and ligand stabilized platinum and palladium nanoparticles. Plasma cleaning to remove the organics results in a conductive metal thin film. We expect that the methods described here can be generalized to other metals, mixtures of metal nanoparticles, and intermetallics. PMID:21567618

Arora, Hitesh; Li, Zihui; Sai, Hiroaki; Kamperman, Marleen; Warren, Scott C; Wiesner, Ulrich

2010-11-15

163

Thin film production method and apparatus  

DOEpatents

A method for forming a thin film material which comprises depositing solid particles from a flowing suspension or aerosol onto a filter and next adhering the solid particles to a second substrate using an adhesive.

Loutfy, Raouf O. (Tucson, AZ); Moravsky, Alexander P. (Tucson, AZ); Hassen, Charles N. (Tucson, AZ)

2010-08-10

164

Thin-film neutron optical devices  

SciTech Connect

This book contains the proceedings of a conference on thin-film neutron optical devices. Topics covered include: Design of high reflectivity supermirror structures; Construction of neutron guide tubes; and Theory of multilayer neutron monochromators.

Majkrzak, C.

1988-01-01

165

Solid State Thin Film Lithium Microbatteries  

E-print Network

Solid state thin film lithium microbatteries fabricated by pulsed-laser deposition (PLD) are suggested. During deposition the following process parameters must be considered, which are laser energy and fluence, laser pulse ...

Shi, Z.

166

Raman spectroscopy of KTN thin films  

Microsoft Academic Search

The renewed interest in the KTa1-x-NbxO (KTN) mixed perovskite materials, especially in single crystalline thin film forms, is connected with their remarkable dielectric properties in the dilute compositions. Off-center Nb ions in the highly polarizable KTaO3 lattice provide a drastic increase in the dielectric peak up to 20 times in comparison with pure KTaO3 and KNbO3. KTN thin films with

I. G. Siny; A. A. Savvinov; R. S. Katiyar; L. A. Knauss

1999-01-01

167

Thin-film reliability and engineering overview  

NASA Technical Reports Server (NTRS)

The reliability and engineering technology base required for thin film solar energy conversions modules is discussed. The emphasis is on the integration of amorphous silicon cells into power modules. The effort is being coordinated with SERI's thin film cell research activities as part of DOE's Amorphous Silicon Program. Program concentration is on temperature humidity reliability research, glass breaking strength research, point defect system analysis, hot spot heating assessment, and electrical measurements technology.

Ross, R. G., Jr.

1984-01-01

168

Printable CIGS thin film solar cells  

NASA Astrophysics Data System (ADS)

Among the various thin film solar cells in the market, CuInGaSe thin film solar cells have been considered as the most promising alternatives to crystalline silicon solar cells because of their high photo-electricity conversion efficiency, reliability, and stability. However, many fabrication methods of CIGS thin film are based on vacuum processes such as evaporation and sputtering techniques which are not cost efficient. This work develops a solution method using paste or ink liquid spin-coated on glass that would be competitive to conventional ways in terms of cost effective, non-vacuum needed, and quick processing. A mixture precursor was prepared by dissolving appropriate amounts of composition chemicals. After the mixture solution was cooled, a viscous paste was prepared and ready for spin-coating process. A slight bluish CIG thin film on substrate was then put in a tube furnace with evaporation of metal Se followed by depositing CdS layer and ZnO nanoparticle thin film coating to complete a solar cell fabrication. Structure, absorption spectrum, and photo-electricity conversion efficiency for the as-grown CIGS thin film solar cell are under study.

Fan, Xiaojuan

2013-03-01

169

Photophysical properties of Alq3 thin films  

NASA Astrophysics Data System (ADS)

This work contains investigation results of the photophysical properties of aluminum (III) tris(8-hydroxyquinoline) thin films. The Alq3 thin films were successfully fabricated by Physical Vapor Deposition technique. The films were grown on transparent: (quartz and glass) and semiconductor (n-type silica) substrates kept at room temperature during the deposition process. Selected films were annealed after fabrication in ambient atmosphere for 12 h at the temperature equal to 100 °C and 150 °C. Morphology of the films was investigated by AFM technique. Photophysical properties were characterized via photoluminescence, transmission, second and third harmonic generation measurements. The thin films exhibit high structural quality regardless of the annealing process, but the stability of the film can be improved by using an appropriate temperature during the annealing process. Photoluminescence of Alq3 films obtained in air were efficient and stable. The measurements of transmission, SHG and THG spectra allowed us to determine optical constant of the films. We find that the photophysical properties were strictly connected with the morphology and the annealing process significantly changes the structural properties of the films.

Zawadzka, A.; P?óciennik, P.; Strzelecki, J.; ?ukasiak, Z.; Sahraoui, B.

2013-11-01

170

Thin wetting film lensless imaging  

NASA Astrophysics Data System (ADS)

Lensless imaging has recently attracted a lot of attention as a compact, easy-to-use method to image or detect biological objects like cells, but failed at detecting micron size objects like bacteria that often do not scatter enough light. In order to detect single bacterium, we have developed a method based on a thin wetting film that produces a micro-lens effect. Compared with previously reported results, a large improvement in signal to noise ratio is obtained due to the presence of a micro-lens on top of each bacterium. In these conditions, standard CMOS sensors are able to detect single bacterium, e.g. E.coli, Bacillus subtilis and Bacillus thuringiensis, with a large signal to noise ratio. This paper presents our sensor optimization to enhance the SNR; improve the detection of sub-micron objects; and increase the imaging FOV, from 4.3 mm2 to 12 mm2 to 24 mm2, which allows the detection of bacteria contained in 0.5?l to 4?l to 10?l, respectively.

Allier, C. P.; Poher, V.; Coutard, J. G.; Hiernard, G.; Dinten, J. M.

2011-03-01

171

RF surface resistance of YBa2Cu3O(7-x) thin films  

NASA Technical Reports Server (NTRS)

The excitement engendered by the discovery of the new T sub c oxide superconductors has led to much speculation about practical applications of thin films of these materials in digital and analog electronic devices. Most of these envisioned applications involve high frequency signals for which a detailed knowledge of the surface impedance of the novel superconductors is very important. We have measured the surface resistance of thin films of YBaCuO in the frequency range 0.5 less than f less than 17 GHz using a stripline-resonator method. The stripline procedure also was used to measure the surface resistance of high quality gold and aluminum films; the resistance values obtained agree with values predicted from the measured dc resistance using the Pippard formalism for the anomalous skin effect. The YBaCuO were produced by a multilayer deposition process. The films are formed by e-beam evaporation of 24 layers of Y, Ba, and Cu. Films with the highest transition temperature were obtained using yttria-stabilized zirconia (YSZ) substrates. After deposition, the films are transferred to a furnace where they are annealed in flowing O2 at 850 C for 2h. The furnace then is turned off and allowed to cool to 100 C in about 16 h. Auger profiling of the films made by this process shows that the concentrations of Y, Ba, Cu, and O are uniform to within 1 percent throughout the thickness of the film.

1988-01-01

172

Thin films, asphaltenes, and reservoir wettability  

SciTech Connect

Reservoir wettability impacts the success of oil recovery by waterflooding and other methods. To understand wettability and its alteration, thin-film forces in solid-aqueous-oil systems must be elucidated. Upon rupture of thick aqueous films separating the oil and rock phases, asphaltene components in the crude oil adsorb irreversibly on the solid surface, changing it from water-wet to oil-wet. Conditions of wettability alteration can be found by performing adhesion tests, in which an oil droplet is brought into contact with a solid surface. Exceeding a critical capillary pressure destabilizes the film, causing spontaneous film rupture to a molecularly adsorbed layer and oil adhesion accompanied by pinning at the three-phase contact line. The authors conduct adhesion experiments similar to those of Buckley and Morrow and simultaneously examine the state of the underlying thin film using optical microscopy and microinterferometry. Aqueous thin films between an asphaltic Orcutt crude oil and glass surfaces are studied as a function of aqueous pH and salinity. For the first time, they prove experimentally that strongly water-wet to strongly oil-wet wettability alteration and contact-angle pinning occur when thick aqueous films thin to molecularly adsorbed films and when the oil phase contains asphaltene molecules.

Kaminsky, R.; Bergeron, V.; Radke, C.J. [Lawrence Berkeley Lab., CA (United States)]|[California Univ., Berkeley, CA (United States). Dept. of Chemical Engineering

1993-04-01

173

Dynamics of liquid films and thin jets  

Microsoft Academic Search

The theory of liquid films and thin jets as one- and two-dimensional continuums is examined. The equations of motion have led to solutions for the characteristic speeds of wave propagation for the parameters characterizing the shape. The formal analogy with a compressible fluid indicates the possibility of shock wave generation in films and jets and the formal analogy to the

Michail Zak

1979-01-01

174

Casimir effect for thin films in QED  

Microsoft Academic Search

We consider the problem of modelling of interaction of thin material films with fields of quantum electrodynamics. Taking into account the basic principles of quantum electrodynamics (locality, gauge invariance, renormalizability), we construct a single model for Casimir-like phenomena arising near the film boundary at distances much larger than the Compton wavelength of the electron. In this region, contribution of fluctuations

V. N. Markov; Yu M. Pis'mak

2006-01-01

175

Casimir effect for thin films in QED  

Microsoft Academic Search

We consider the problem of modeling of interaction of thin material films with fields of quantum electrodynamics. Taking into account the basic principles of quantum electrodynamics (locality, gauge invariance, renormalizability) we construct a single model for Casimir-like phenomena arising near the film boundary on distances much larger then Compton wavelength of the electron. In this region contribution of Dirac fields

V N Markovand; Yu M Pis

176

Surface Plasmons in Thin Metallic Films  

E-print Network

For the first time it is shown that for thin metallic films thickness of which not exceed thickness of skin -- layer, the problem of description of surface plasma oscillations allows analytical solution by arbitrary ratio between length of electrons free path and thickness of a film. The dependance of frequency surface plasma oscillations on wave number is carry out.

A. V. Latyshev; A. A. Yushkanov

2010-10-11

177

Phase evolution in boron nitride thin films  

Microsoft Academic Search

Boron nitride (BN) thin films were deposited on monocrystalline Si (100) wafers using electron beam evaporation of boron with simultaneous bombardment by nitrogen and argon ions. The effect of film thickness on the resultant BN phase was investigated using Fourier transform infrared (FTIR) spectroscopy and high resolution transmission electron microscopy (HRTEM). These techniques revealed the consecutive deposition of an initial

D. J. Kester; K. S. Ailey; R. F. Davis; K. L. More

1993-01-01

178

Induced electronic anisotropy in bismuth thin films  

NASA Astrophysics Data System (ADS)

We use magneto-resistance measurements to investigate the effect of texturing in polycrystalline bismuth thin films. Electrical current in bismuth films with texturing such that all grains are oriented with the trigonal axis normal to the film plane is found to flow in an isotropic manner. By contrast, bismuth films with no texture such that not all grains have the same crystallographic orientation exhibit anisotropic current flow, giving rise to preferential current flow pathways in each grain depending on its orientation. Extraction of the mobility and the phase coherence length in both types of films indicates that carrier scattering is not responsible for the observed anisotropic conduction. Evidence from control experiments on antimony thin films suggests that the anisotropy is a result of bismuth's large electron effective mass anisotropy.

Liao, Albert D.; Yao, Mengliang; Katmis, Ferhat; Li, Mingda; Tang, Shuang; Moodera, Jagadeesh S.; Opeil, Cyril; Dresselhaus, Mildred S.

2014-08-01

179

Adhesion and friction of thin metal films  

NASA Technical Reports Server (NTRS)

Sliding friction experiments were conducted in vacuum with thin films of titanium, chromium, iron, and platinum sputter deposited on quartz or mica substrates. A single crystal hemispherically tipped gold slider was used in contact with the films at loads of 1.0 to 30.0 and at a sliding velocity of 0.7 mm/min at 23 C. Test results indicate that the friction coefficient is dependent on the adhesion of two interfaces, that between the film and its substrate and the slider and the film. There exists a relationship between the percent d bond character of metals in bulk and in thin film form and the friction coefficient. Oxygen can increase adhesive bonding of a metal film (platinum) to a substrate.

Buckley, D. H.

1976-01-01

180

Polysilicon Super-Thin-Film Transistor (SFT)  

Microsoft Academic Search

N-channel MOS FET's have been fabricated in super-thin polysilicon film on quartz substrate. The thickness of the film had an important role in improving the electrical properties. Moreover, grain boundary passivation by the hydrogen from a plasma-SiN film has been developed to increase the field effect mobility. The field effect mobility is more than 20 cm2\\/V\\\\cdots at the polysilicon thickness

Hisao Hayashi; Takashi Noguchi; Takefumi Oshima

1984-01-01

181

Flexible Thin Metal Film Thermal Sensing System  

NASA Technical Reports Server (NTRS)

A flexible thin metal film thermal sensing system is provided. A thermally-conductive film made from a thermally-insulating material is doped with thermally-conductive material. At least one layer of electrically-conductive metal is deposited directly onto a surface of the thermally-conductive film. One or more devices are coupled to the layer(s) to measure an electrical characteristic associated therewith as an indication of temperature.

Thomsen, Donald Laurence (Inventor)

2012-01-01

182

Study of iron mononitride thin films  

SciTech Connect

In this work we have studied the crystal structural and local ordering of iron and nitrogen in iron mononitride thin films prepared using dc magnetron sputtering at sputtering power of 100W and 500W. The films were sputtered using pure nitrogen to enhance the reactivity of nitrogen with iron. The x-ray diffraction (XRD), conversion electron Mössbauer spectroscopy (CEMS) and soft x-ray absorption spectroscopy (SXAS) studies shows that the film crystallizes in ZnS-type crystal structure.

Tayal, Akhil, E-mail: mgupta@csr.res.in; Gupta, Mukul, E-mail: mgupta@csr.res.in; Phase, D. M., E-mail: mgupta@csr.res.in; Reddy, V. R., E-mail: mgupta@csr.res.in; Gupta, Ajay, E-mail: mgupta@csr.res.in [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore,-452001 (India)

2014-04-24

183

Study of iron mononitride thin films  

NASA Astrophysics Data System (ADS)

In this work we have studied the crystal structural and local ordering of iron and nitrogen in iron mononitride thin films prepared using dc magnetron sputtering at sputtering power of 100W and 500W. The films were sputtered using pure nitrogen to enhance the reactivity of nitrogen with iron. The x-ray diffraction (XRD), conversion electron Mössbauer spectroscopy (CEMS) and soft x-ray absorption spectroscopy (SXAS) studies shows that the film crystallizes in ZnS-type crystal structure.

Tayal, Akhil; Gupta, Mukul; Phase, D. M.; Reddy, V. R.; Gupta, Ajay

2014-04-01

184

Auger electron spectra of Mg thin films  

Microsoft Academic Search

The effect of oxidation on Mg thin films is studied by Auger electron spectroscopy. Several films are prepared from Mg of purity 99.999% under a pressure of 10-6-10-8 Torr in the thickness range 200-25 000 ÅA. The spectra from these films are measured on an ESCA-36 spectrometer with Al Kalpha excitation line under a pressure of about 10-8 Torr. The

N. C. Halder; J. Alonso Jr.; W. E. Swartz Jr.

1976-01-01

185

Electrostatic tuning of the properties of disordered indium-oxide films near the superconductor-insulator transition  

NASA Astrophysics Data System (ADS)

The evolution with carrier concentration of the electrical properties of amorphous indium oxide (InOx) thin films has been studied using electric double-layer transistor configurations. Carrier variations of up to 7×1014carriers/cm2 were achieved using an ionic liquid as a gate dielectric. The superconductor-insulator transition was traversed, and the magnitude and position of the large magnetoresistance peak found in the insulating regime were modified. The systematic variation of the magnetoresistance peak with charge concentration was found to be qualitatively consistent with a simulation based on a model involving granularity.

Lee, Yeonbae; Frydman, Aviad; Chen, Tianran; Skinner, Brian; Goldman, A. M.

2013-07-01

186

Thin film thermocouples for internal combustion engines  

NASA Astrophysics Data System (ADS)

Procedures for fabricating thin film thermocouples on internal combustion engine hardware are examined experimentally. The techniques for growing a thermal oxide on cast iron, ferritic steel, and austenitic steel samples, representing engine hardware, with an FeCrAlY coating using an Al2O3 insulation layer are described. The adhesion, stability, and electrical performance of the aluminum oxide coating and platinum plus platinum-rhodium thermocouple films are analyzed. It is observed that thin film sputtered thermocouples of platinum plus platinum-rhodium can be fabricated on iron-base alloys using Al2O3 insulation formed thermally on FeCrAlY and by reactive sputtering.

Kreider, Kenneth G.

1986-12-01

187

Thin-film rechargeable lithium batteries  

SciTech Connect

Thin-film rechargeable lithium batteries using ceramic electrolyte and cathode materials have been fabricated by physical deposition techniques. The lithium phosphorous oxynitride electrolyte has exceptional electrochemical stability and a good lithium conductivity. The lithium insertion reaction of several different intercalation materials, amorphous V{sub 2}O{sub 5}, amorphous LiMn{sub 2}O{sub 4}, and crystalline LiMn{sub 2}O{sub 4} films, have been investigated using the completed cathode/electrolyte/lithium thin-film battery.

Dudney, N.J.; Bates, J.B.; Lubben, D. [Oak Ridge National Lab., TN (United States). Solid State Div.

1995-06-01

188

Ambient pressure process for preparing aerogel thin films reliquified sols useful in preparing aerogel thin films  

DOEpatents

A method for preparing aerogel thin films by an ambient-pressure, continuous process. The method of this invention obviates the use of an autoclave and is amenable to the formation of thin films by operations such as dip coating. The method is less energy intensive and less dangerous than conventional supercritical aerogel processing techniques.

Brinker, Charles Jeffrey (Albuquerque, NM); Prakash, Sai Sivasankaran (Minneapolis, MN)

1999-01-01

189

Method for making thin polypropylene film  

DOEpatents

An economical method is provided for making uniform thickness polypropylene film as thin as 100 Angstroms. A solution of polypropylene dissolved in xylene is formed by mixing granular polypropylene and xylene together in a flask at an elevated temperature. A substrate, such as a glass plate or microscope slide is immersed in the solution. When the glass plate is withdrawn from the solution at a uniform rate, a thin polypropylene film forms on a flat surface area of the glass plate as the result of xylene evaporation. The actual thickness of the polypropylene film is functional of the polypropylene in xylene solution concentration, and the particular withdrawal rate of the glass plate from the solution. After formation, the thin polypropylene film is floated from the glass plate onto the surface of water, from which it is picked up with a wire hoop.

Behymer, R.D.; Scholten, J.A.

1985-11-21

190

Magnetoelectric thin film composites with interdigital electrodes  

NASA Astrophysics Data System (ADS)

Magnetoelectric (ME) thin film composites on silicon cantilevers are fabricated using Pb(Zr0.52Ti0.45)O3 (PZT) films with interdigital transducer electrodes on the top side and FeCoSiB amorphous magnetostrictive thin films on the backside. These composites without any direct interface between the piezoelectric and magnetostrictive phase are superior to conventional plate capacitor-type thin film ME composites. A limit of detection of 2.6 pT/Hz1/2 at the mechanical resonance is determined which corresponds to an improvement of a factor of approximately 2.8 compared to the best plate type sensor using AlN as the piezoelectric phase and even a factor of approximately 4 for a PZT plate capacitor.

Piorra, A.; Jahns, R.; Teliban, I.; Gugat, J. L.; Gerken, M.; Knöchel, R.; Quandt, E.

2013-07-01

191

Nanostructured thin films as functional coatings  

NASA Astrophysics Data System (ADS)

Nanostructured thin films is one of the highly exploiting research areas particularly in applications such as photovoltaics, photocatalysis and sensor technologies. Highly tuned thin films, in terms of thickness, crystallinity, porosity and optical properties, can be fabricated on different substrates using the sol-gel method, chemical solution deposition (CSD), electrochemical etching, along with other conventional methods such as chemical vapour deposition (CVD) and physical vapour deposition (PVD). The above mentioned properties of these films are usually characterised using surface analysis techniques such as XRD, SEM, TEM, AFM, ellipsometry, electrochemistry, SAXS, reflectance spectroscopy, STM, XPS, SIMS, ESCA, X-ray topography and DOSY-NMR. This article presents a short review of the preparation and characterisation of thin films of nanocrystalline titanium dioxide and modified silicon as well as their application in solar cells, water treatment, water splitting, self cleaning fabrics, sensors, optoelectronic devices and lab on chip systems.

Lazar, Manoj A.; Tadvani, Jalil K.; Sze Tung, Wing; Lopez, Lorena; Daoud, Walid A.

2010-06-01

192

LPG sensing performance of nanostructured zinc oxide thin films  

NASA Astrophysics Data System (ADS)

Nanostructured zinc oxide thin films were prepared using ultrasonic spray pyrolysis technique. Zinc acetate was used as a starting precursor. As prepared thin films were characterized using different analytical techniques. The sensing performance of the nanostructured zinc oxide thin films was studied on exposure of various gases. The films were observed to be most sensitive (S= 1727) to LPG at 300°C.

Bari, A. R.; Patil, L. A.

2013-06-01

193

NANO-INDENTATION OF COPPER THIN FILMS ON SILICON SUBSTRATES  

E-print Network

NANO-INDENTATION OF COPPER THIN FILMS ON SILICON SUBSTRATES S. Suresh1 , T.-G. Nieh2 and B.W. Choi2: Mechanical properties; Nano-indentation; Thin films; Copper; Dislocations Introduction Indentation methods films on substrates (e.g., [2,3]) using instrumented indentation. Nano-indentation studies of thin films

Suresh, Subra

194

Annotated bibliography on thin film technology, supplement II  

Microsoft Academic Search

The major subject areas covered are: materials, properties, electrical characteristics of thin films; passive and active components; techniques, theory and mechanisms; applications; radiation effects; superconductivity of thin films; magnetic films; and failure studies in this field. A new subdivision on thin film memories has been added to this supplement. There are 1142 references, which include books, reports, papers, and periodical

Lyau; C. F. G

1965-01-01

195

June 26, 2000 1 Fracture in Thin Films  

E-print Network

June 26, 2000 1 Fracture in Thin Films Z. Suo Mechanical and Aerospace Engineering Department Science in 2001 #12;June 26, 2000 2 4.2.1.i Fracture in Thin Films Thin films are grown on substrates, silicon nitride films as environmental barriers on metals and polymers in microprocessors, and gallium

Suo, Zhigang

196

Mesoscopically structured nanocrystalline metal oxide thin films  

NASA Astrophysics Data System (ADS)

This review describes the main successful strategies that are used to grow mesostructured nanocrystalline metal oxide and SiO2 films via deposition of sol-gel derived solutions. In addition to the typical physicochemical forces to be considered during crystallization, mesoporous thin films are also affected by the substrate-film relationship and the mesostructure. The substrate can influence the crystallization temperature and the obtained crystallographic orientation due to the interfacial energies and the lattice mismatch. The mesostructure can influence the crystallite orientation, and affects nucleation and growth behavior due to the wall thickness and pore curvature. Three main methods are presented and discussed: templated mesoporosity followed by thermally induced crystallization, mesostructuration of already crystallized metal oxide nanobuilding units and substrate-directed crystallization with an emphasis on very recent results concerning epitaxially grown piezoelectric structured ?-quartz films via crystallization of amorphous structured SiO2 thin films.

Carretero-Genevrier, Adrian; Drisko, Glenna L.; Grosso, David; Boissiere, Cédric; Sanchez, Clement

2014-11-01

197

AC impedance analysis of polypyrrole thin films  

NASA Technical Reports Server (NTRS)

The AC impedance spectra of thin polypyrrole films were obtained at open circuit potentials from -0.4 to 0.4 V vs SCE. Two limiting cases are discussed for which simplified equivalent circuits are applicable. At very positive potentials, the predominantly nonfaradaic AC impedance of polypyrrole is very similar to that observed previously for finite porous metallic films. Modeling of the data with the appropriate equivalent circuit permits effective pore diameter and pore number densities of the oxidized film to be estimated. At potentials from -0.4 to -0.3 V, the polypyrrole film is essentially nonelectronically conductive and diffusion of polymer oxidized sites with their associated counterions can be assumed to be linear from the film/substrate electrode interface. The equivalent circuit for the polypyrrole film at these potentials is that previously described for metal oxide, lithium intercalation thin films. Using this model, counterion diffusion coefficients are determined for both semi-infinite and finite diffusion domains. In addition, the limiting low frequency resistance and capacitance of the polypyrrole thin fims was determined and compared to that obtained previously for thicker films of the polymer. The origin of the observed potential dependence of these low frequency circuit components is discussed.

Penner, Reginald M.; Martin, Charles R.

1987-01-01

198

Mirrorlike pulsed laser deposited tungsten thin film  

SciTech Connect

Mirrorlike tungsten thin films on stainless steel substrate deposited via pulsed laser deposition technique in vacuum (10{sup -5} Torr) is reported, which may find direct application as first mirror in fusion devices. The crystal structure of tungsten film is analyzed using x-ray diffraction pattern, surface morphology of the tungsten films is studied with scanning electron microscope and atomic force microscope. The film composition is identified using energy dispersive x-ray. The specular and diffuse reflectivities with respect to stainless steel substrate of the tungsten films are recorded with FTIR spectra. The thickness and the optical quality of pulsed laser deposition deposited films are tested via interferometric technique. The reflectivity is approaching about that of the bulk for the tungsten film of thickness {approx}782 nm.

Mostako, A. T. T.; Khare, Alika [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039 (India); Rao, C. V. S. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)

2011-01-15

199

Solvothermal annealing of block copolymer thin films.  

PubMed

A two-stage annealing process for block copolymer films was introduced consisting of a solvent vapor exposure followed by a thermal cycle. By heating the film but not the chamber, changes in the ambient vapor pressure of the solvent were avoided. Films of block copolymers and homopolymers showed transient nonmonotonic swelling behavior immediately after solvent exposure that was dependent on how the thin film was cast before the anneal. Thermal cycling of the solvent-swelled block copolymer films during the solvent vapor anneal (SVA) caused the films to deswell in 1-10 s and produced well-ordered microdomains in templated 45.5 and 51.5 kg/mol polystyrene-block-polydimethylsiloxane films annealed in toluene and n-heptane vapors for total process times of 30 s to 5 min. PMID:24083573

Gotrik, Kevin W; Ross, C A

2013-11-13

200

Critical temperature of superconducting thin films  

SciTech Connect

The increase in the critical temperature of the superconducting transition in thin films is related to the change, due to the surface bending of the bands, of the electron concentration in samples of finite dimension. The empirical film-thickness dependence of the charge-carrier concentration, known from experiments on semimetal films, is substituted into the BCS formula for the T/sub c/. The resulting expression describes well the thickness dependence of the T/sub c/ for Al, Sn, and In films.

Bukhshtab, E.I.

1980-06-01

201

Thermal conductivity of dielectric thin films  

SciTech Connect

A direct reading thermal comparator has been used to measure the thermal conductivity of dielectric thin-film coatings. In the past, the thermal comparator has been used extensively to measure the thermal conductivity of bulk solids, liquids, and gases. The technique has been extended to thin-film materials by making experimental improvements and by the application of an analytical heat flow model. Our technique also allows an estimation of the thermal resistance of the film/substrate interface which is shown to depend on the method of film deposition. The thermal conductivity of most thin films was found to be several orders of magnitude lower than that of the material in bulk form. This difference is attributed to structural disorder of materials deposited in thin-film form. The experimentation to date has primarily centered on optical coating materials. These coatings, used to enhance the optical properties of components such as lenses and mirrors, are damaged by thermal loads applied in high-power laser applications. It has been widely postulated that there may be a correlation between the thermal conductivity and the damage threshold of these materials.

Lambropoulos, J.C. (Department of Mechanical Engineering, University of Rochester, Rochester, New York 14627 (US)); Jolly, M.R.; Amsden, C.A.; Gilman, S.E.; Sinicropi, M.J.; Diakomihalis, D.; Jacobs, S.D. (Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299)

1989-11-01

202

Thermal conductivity of dielectric thin films  

SciTech Connect

A direct reading thermal comparator has been used to measure the thermal conductivity of dielectric thin film coatings. In the past, the thermal comparator has been used extensively to measure the thermal conductivity of bulk solids, liquids, and gases. The technique has been extended to thin film materials by making experimental improvements and by the application of an analytical heat flow model. Our technique also allows an estimation of the thermal resistance of the film/substrate interface which is shown to depend on the method of film deposition. The thermal conductivity of most thin films was found to be several orders of magnitude lower than that of the material in bulk form. This difference is attributed to structural disorder of materials deposited in thin film form. The experimentation to date has centered primarily on optical coating materials. These coatings, used to enhance the optical properties of components such as lenses and mirrors, are damaged by thermal loads applied in high-power laser applications. It has been widely postulated that there may be a correlation between the thermal conductivity and the damage threshold of these materials. 31 refs., 11 figs., 8 tabs.

Lambropoulos, J.C.; Jolly, M.R.; Amaden, C.A.; Gilman, S.E.; Sinicropi, M.J.; Diakomihalis, D.; Jacobs, S.D.

1989-05-01

203

All thin film magnetoelectric magnetic field sensors.  

NASA Astrophysics Data System (ADS)

We have fabricated prototype ac magnetic field sensors operating at room temperature based on all thin film ME devices showing strong magnetoelectric (ME) coupling. The ME layers consist of a sol-gel derived Pb(Zr0.52Ti0.48)TiO3 (PZT) film and a dc magnetron sputter deposited magnetostrictive Fe70Ga30 (FeGa) film. The bilayer structures are prepared on micromachined Si wafers, and the laser cutting technique is used to release and isolate the cantilevers for optimization of the sensor performance. The PZT layer and the FeGa layer couple via the piezoelectric d31 mode and the corresponding ME coupling coefficient is as high as 2 V/(Oe cm) for a lateral dimension of 1 mm^2 device at the mechanical resonant frequency of 333 Hz of a Si cantilever. The soft magnetic FeGa film requires dc bias magnetic field of around 90 Oe to operate the thin film ME device. The coupling between the PZT and the FeGa films is remarkably improved by depositing a 40 nm thick Pt intermediate layer. The clamping effect on the ME coupling is dramatically reduced by back-etching the Si cantilever down to 35 ?m thick. The present work indicates presence of robust ME coupling in microfabricated multilayer thin film ME devices.

Zhao, Peng

2009-03-01

204

Mesoscale morphologies in polymer thin films.  

SciTech Connect

In the midst of an exciting era of polymer nanoscience, where the development of materials and understanding of properties at the nanoscale remain a major R&D endeavor, there are several exciting phenomena that have been reported at the mesoscale (approximately an order of magnitude larger than the nanoscale). In this review article, we focus on mesoscale morphologies in polymer thin films from the viewpoint of origination of structure formation, structure development and the interaction forces that govern these morphologies. Mesoscale morphologies, including dendrites, holes, spherulites, fractals and honeycomb structures have been observed in thin films of homopolymer, copolymer, blends and composites. Following a largely phenomenological level of description, we review the kinetic and thermodynamic aspects of mesostructure formation outlining some of the key mechanisms at play. We also discuss various strategies to direct, limit, or inhibit the appearance of mesostructures in polymer thin films as well as an outlook toward potential areas of growth in this field of research.

Ramanathan, M.; Darling, S. B. (Center for Nanoscale Materials)

2011-06-01

205

Method for synthesizing thin film electrodes  

DOEpatents

A method for making a thin-film electrode, either an anode or a cathode, by preparing a precursor solution using an alkoxide reactant, depositing multiple thin film layers with each layer approximately 500 1000 .ANG. in thickness, and heating the layers to above 600.degree. C. to achieve a material with electrochemical properties suitable for use in a thin film battery. The preparation of the anode precursor solution uses Sn(OCH.sub.2C(CH.sub.3).sub.3).sub.2 dissolved in a solvent in the presence of HO.sub.2CCH.sub.3 and the cathode precursor solution is formed by dissolving a mixture of (Li(OCH.sub.2C(CH.sub.3).sub.3)).sub.8 and Co(O.sub.2CCH.sub.3).H.sub.2O in at least one polar solvent.

Boyle, Timothy J. (Albuquerque, NM)

2007-03-13

206

Vibration welding system with thin film sensor  

DOEpatents

A vibration welding system includes an anvil, a welding horn, a thin film sensor, and a process controller. The anvil and horn include working surfaces that contact a work piece during the welding process. The sensor measures a control value at the working surface. The measured control value is transmitted to the controller, which controls the system in part using the measured control value. The thin film sensor may include a plurality of thermopiles and thermocouples which collectively measure temperature and heat flux at the working surface. A method includes providing a welder device with a slot adjacent to a working surface of the welder device, inserting the thin film sensor into the slot, and using the sensor to measure a control value at the working surface. A process controller then controls the vibration welding system in part using the measured control value.

Cai, Wayne W; Abell, Jeffrey A; Li, Xiaochun; Choi, Hongseok; Zhao, Jingzhou

2014-03-18

207

Thin film ferroelectric electro-optic memory  

NASA Technical Reports Server (NTRS)

An electrically programmable, optically readable data or memory cell is configured from a thin film of ferroelectric material, such as PZT, sandwiched between a transparent top electrode and a bottom electrode. The output photoresponse, which may be a photocurrent or photo-emf, is a function of the product of the remanent polarization from a previously applied polarization voltage and the incident light intensity. The cell is useful for analog and digital data storage as well as opto-electric computing. The optical read operation is non-destructive of the remanent polarization. The cell provides a method for computing the product of stored data and incident optical data by applying an electrical signal to store data by polarizing the thin film ferroelectric material, and then applying an intensity modulated optical signal incident onto the thin film material to generate a photoresponse therein related to the product of the electrical and optical signals.

Thakoor, Sarita (Inventor); Thakoor, Anilkumar P. (Inventor)

1993-01-01

208

Thin Film Transistors On Plastic Substrates  

DOEpatents

A process for formation of thin film transistors (TFTs) on plastic substrates replaces standard thin film transistor fabrication techniques, and uses sufficiently lower processing temperatures so that inexpensive plastic substrates may be used in place of standard glass, quartz, and silicon wafer-based substrates. The silicon based thin film transistor produced by the process includes a low temperature substrate incapable of withstanding sustained processing temperatures greater than about 250.degree. C., an insulating layer on the substrate, a layer of silicon on the insulating layer having sections of doped silicon, undoped silicon, and poly-silicon, a gate dielectric layer on the layer of silicon, a layer of gate metal on the dielectric layer, a layer of oxide on sections of the layer of silicon and the layer of gate metal, and metal contacts on sections of the layer of silicon and layer of gate metal defining source, gate, and drain contacts, and interconnects.

Carey, Paul G. (Mountain View, CA); Smith, Patrick M. (San Ramon, CA); Sigmon, Thomas W. (Portola Valley, CA); Aceves, Randy C. (Livermore, CA)

2004-01-20

209

Feasibility Study of Thin Film Thermocouple Piles  

NASA Technical Reports Server (NTRS)

Historically, thermopile detectors, generators, and refrigerators based on bulk materials have been used to measure temperature, generate power for spacecraft, and cool sensors for scientific investigations. New potential uses of small, low-power, thin film thermopiles are in the area of microelectromechanical systems since power requirements decrease as electrical and mechanical machines shrink in size. In this research activity, thin film thermopile devices are fabricated utilizing radio frequency sputter coating and photoresist lift-off techniques. Electrical characterizations are performed on two designs in order to investigate the feasibility of generating small amounts of power, utilizing any available waste heat as the energy source.

Sisk, R. C.

2001-01-01

210

Dielectric breakdown of PDMS thin films  

NASA Astrophysics Data System (ADS)

This note presents the data on the dielectric breakdown of polydimethylsiloxane (PDMS) thin films with thicknesses from 2?to 14??m between the silicon electrodes. The results demonstrate that there is a strong dependence of the breakdown field on both the electrode gap and shape. The breakdown fields range from 250 to 635 V ?m-1, depending on the electrode geometry and gap, approaching 10× the breakdown fields for air gaps of the same size. The results are critical for understanding the performance limits of PDMS thin films used in the electromechanical microsystems.

Gerratt, Aaron P.; Bergbreiter, Sarah

2013-06-01

211

Borocarbide thin films and tunneling measurements.  

SciTech Connect

The results obtained by their group in thin film fabrication and STM tunneling on superconducting borocarbides YNi{sub 2}B{sub 2}C have been be briefly reviewed. Results concerning the microwave surface impedance and the S/N planar junctions on LuNi{sub 2}B{sub 2}C thin films have been also presented and analyzed. These new data unambiguously confirm the full BCS nature of the superconducting gap in borocarbides and the absence of significant pair-breaking effects in LuNi{sub 2}B{sub 2}C.

Iavarone, M.; Andreone, A.; Cassinese, A.; Dicapual, R.; giannil, L.; Vagliol, R.; DeWilde, Y.; Crabtree, G. W.

2000-06-15

212

Emittance Theory for Thin Film Selective Emitter  

NASA Technical Reports Server (NTRS)

Thin films of high temperature garnet materials such as yttrium aluminum garnet (YAG) doped with rare earths are currently being investigated as selective emitters. This paper presents a radiative transfer analysis of the thin film emitter. From this analysis the emitter efficiency and power density are calculated. Results based on measured extinction coefficients for erbium-YAG and holmium-YAG are presented. These results indicated that emitter efficiencies of 50 percent and power densities of several watts/sq cm are attainable at moderate temperatures (less than 1750 K).

Chubb, Donald L.; Lowe, Roland A.; Good, Brian S.

1994-01-01

213

Micro-sensor thin-film anemometer  

NASA Technical Reports Server (NTRS)

A device for measuring turbulence in high-speed flows is provided which includes a micro-sensor thin-film probe. The probe is formed from a single crystal of aluminum oxide having a 14.degree. half-wedge shaped portion. The tip of the half-wedge is rounded and has a thin-film sensor attached along the stagnation line. The bottom surface of the half-wedge is tilted upward to relieve shock induced disturbances created by the curved tip of the half-wedge. The sensor is applied using a microphotolithography technique.

Sheplak, Mark (Inventor); McGinley, Catherine B. (Inventor); Spina, Eric F. (Inventor); Stephens, Ralph M. (Inventor); Hopson, Jr., Purnell (Inventor); Cruz, Vincent B. (Inventor)

1996-01-01

214

The interplay between spatially separated ferromagnetic and superconducting thin films  

E-print Network

Ferromagnetic thin films have been grown via physical vapor deposition utilizing the technique of flash evaporation and characterized by measuring magnetization as a function of magnetic field. An Al thin film was evaporated atop the ferromagnetic...

Sullivan, Isaac John

2013-02-22

215

Dynamics and stability of thin liquid films  

NASA Astrophysics Data System (ADS)

The dynamics and stability of thin liquid films have fascinated scientists over many decades: the observations of regular wave patterns in film flows down a windowpane or along guttering, the patterning of dewetting droplets, and the fingering of viscous flows down a slope are all examples that are familiar in daily life. Thin film flows occur over a wide range of length scales and are central to numerous areas of engineering, geophysics, and biophysics; these include nanofluidics and microfluidics, coating flows, intensive processing, lava flows, dynamics of continental ice sheets, tear-film rupture, and surfactant replacement therapy. These flows have attracted considerable attention in the literature, which have resulted in many significant developments in experimental, analytical, and numerical research in this area. These include advances in understanding dewetting, thermocapillary- and surfactant-driven films, falling films and films flowing over structured, compliant, and rapidly rotating substrates, and evaporating films as well as those manipulated via use of electric fields to produce nanoscale patterns. These developments are reviewed in this paper and open problems and exciting research avenues in this thriving area of fluid mechanics are also highlighted.

Craster, R. V.; Matar, O. K.

2009-07-01

216

Oxynitride Thin Film Barriers for PV Packaging  

Microsoft Academic Search

Dielectric thin-film barrier and adhesion-promoting layers consisting of silicon oxynitride materials (SiOxNy, with various stoichiometry) were investigated. For process development, films were applied to glass (TCO, conductive SnO2:F; or soda-lime), polymer (PET, polyethylene terephthalate), aluminized soda-lime glass, or PV cell (a-Si, CIGS) substrates. Design strategy employed de-minimus hazard criteria to facilitate industrial adoption and reduce implementation costs for PV manufacturers

S. H. Glick; J. A. delCueto; K. M. Terwilliger; G. J. Jorgensen; J. W. Pankow; B. M. Keyes; L. M. Gedvilas; F. J. Pern

2005-01-01

217

Oxidation mechanisms in WSi2 thin films  

Microsoft Academic Search

The utilization of WSi2 thin films as gate electrodes in field-effect transistors depends on the ability of this material to form a continuous electrically insulating SiO2 overlayer. In the steam oxidation of WSi2 films deposited on polysilicon, SiO2 forms on the surface by means of the rapid diffusion of Si through the WSi2 which appears in this case to be

S. Zirinsky; W. Hammer; F. D'Heurle; J. Baglin

1978-01-01

218

Galvanic deposition of cadmium sulfide thin films  

Microsoft Academic Search

A technique is presented for the deposition of high quality cadmium sulfide (CdS) thin films onto SnO2 substrates by a galvanic method. Single phase films were deposited in a bath of cadmium chloride and sodium thiosulfate at pH = 4 and temperature = 85°C at a growth rate of 1 nm\\/min. In the pH range of 3 to 4, the

B. E. McCandless; A. Mondal; R. W. Birkmire

1995-01-01

219

Perovskite Thin Films via Atomic Layer Deposition.  

PubMed

A new method to deposit perovskite thin films that benefit from the thickness control and conformality of atomic layer deposition (ALD) is detailed. A seed layer of ALD PbS is place-exchanged with PbI2 and subsequently CH3 NH3 PbI3 perovskite. These films show promising optical properties, with gain coefficients of 3200 ± 830 cm(-1) . PMID:25359103

Sutherland, Brandon R; Hoogland, Sjoerd; Adachi, Michael M; Kanjanaboos, Pongsakorn; Wong, Chris T O; McDowell, Jeffrey J; Xu, Jixian; Voznyy, Oleksandr; Ning, Zhijun; Houtepen, Arjan J; Sargent, Edward H

2015-01-01

220

Superconducting thin films on potassium tantalate substrates  

DOEpatents

A superconductive system for the lossless transmission of electrical current comprising a thin film of superconducting material Y.sub.1 Ba.sub.2 Cu.sub.3 O.sub.7-x epitaxially deposited upon a KTaO.sub.3 substrate. The KTaO.sub.3 is an improved substrate over those of the prior art since the it exhibits small lattice constant mismatch and does not chemically react with the superconducting film.

Feenstra, Roeland (Oak Ridge, TN); Boatner, Lynn A. (Oak Ridge, TN)

1992-01-01

221

Viscous fingering in volatile thin films  

E-print Network

A thin water film on a cleaved mica substrate undergoes a first order phase transition between two values of film thickness. By inducing a finite evaporation rate of the water, the interface between the two phases develops a fingering instability similar to that observed in the Saffman-Taylor problem. We draw the connection between the two problems, and construct solutions describing the dynamics of evaporation in this system.

Oded Agam

2008-09-02

222

Epitaxial decagonal thin films on crystalline substrates  

Microsoft Academic Search

Al-Cu-Fe-Cr quasicrystalline thin films were grown on atomically flat Al 2 O 3 sapphire (0001) substrates by single-target magnetron sputtering followed by annealing. A decagonal phase with the tenfold axis A 10 parallel to the substrate surface normal was observed. The epitaxial decagonal film had two different unique orientations: a twofold P axis A 2P and a twofold D axis

E. J. Widjajay; L. D. Marks

2003-01-01

223

Epitaxial decagonal thin films on crystalline substrates  

Microsoft Academic Search

Al-Cu-Fe-Cr quasicrystalline thin films were grown on atomically flat Al2O3 sapphire (0001) substrates by single-target magnetron sputtering followed by annealing. A decagonal phase with the tenfold axis A10 parallel to the substrate surface normal was observed. The epitaxial decagonal film had two different unique orientations: a twofold P axis A2P and a twofold D axis A2D parallel to of the

E. J. Widjaja; L. D. Marks

2003-01-01

224

Oriented thin films of perylenetetracarboxylic diimide on frictiontransferred polymer films  

NASA Astrophysics Data System (ADS)

Perylenetetracarboxylic diimide (PTCDI) is a promising material for application in organic electronics. In this study we report on the preparation of oriented thin films of PTCDI on the surface of oriented polymer substrates, which were prepared by friction transfer method. Two polymers, poly(tetrafluoroethylene) (PTFE) and poly(p-phenylene) (PPP) were used as the orienting substrate for PTCDI for comparison studies. Characterization by polarized UV-vis absorption shows that the orienting ability of PPP is larger than that of PTFE substrate. Furthermore, polarization-sensitive photoelectric conversion devices were fabricated by using the oriented PTCDI thin film on the PPP substrate.

Tanigaki, Nobutaka; Heck, Claire; Mizokuro, Toshiko

225

Preface: Thin films of molecular organic materials  

NASA Astrophysics Data System (ADS)

This special issue is devoted to thin films of molecular organic materials and its aim is to assemble numerous different aspects of this topic in order to reach a wide scientific audience. Under the term 'thin films', structures with thicknesses spanning from one monolayer or less up to several micrometers are included. In order to narrow down this relaxed definition (how thin is thin?) I suggest joining the stream that makes a distinction according to the length scale involved, separating nanometer-thick films from micrometer-thick films. While the physical properties of micrometer-thick films tend to mimic those of bulk materials, in the low nanometer regime new structures (e.g., crystallographic and substrate-induced phases) and properties are found. However, one has to bear in mind that some properties of micrometer-thick films are really confined to the film/substrate interface (e.g. charge injection), and are thus of nanometer nature. Supported in this dimensionality framework, this issue covers the most ideal and model 0D case, a single molecule on a surface, through to the more application-oriented 3D case, placing special emphasis on the fascinating 2D domain that is monolayer assembly. Thus, many aspects will be reviewed, such as single molecules, self-organization, monolayer regime, chirality, growth, physical properties and applications. This issue has been intentionally restricted to small molecules, thus leaving out polymers and biomolecules, because for small molecules it is easier to establish structure--property relationships. Traditionally, the preparation of thin films of molecular organic materials has been considered as a secondary, lower-ranked part of the more general field of this class of materials. The coating of diverse surfaces such as silicon, inorganic and organic single crystals, chemically modified substrates, polymers, etc., with interesting molecules was driven by the potential applications of such molecular materials/substrate systems (also called heterostructures) based on the physical properties of the bulk materials, usually in the form of single crystals. However, in recent years the thin films community has been continually growing, helping the field to mature. In my opinion two main aspects have advanced the thin molecular films field. The first is the different applications with optical and electrical devices such as OFETs (organic field-effect transistors) and OLEDs (organic light emitting diodes), applications that could not have been achieved with single crystals because of limited size, difficult processability and mechanical fragility. The second is the involvement of the surface science community with their overwhelming arsenal of experimental techniques. From the synthesis point of view, the preparation of thin films is being regarded as a complementary synthesis route. The different externally accessible variables involved in the preparation process (temperature, pressure, molecular flux, distance, time, concentration, solvent, substrate, etc.), which define the so-called parameter hyperspace, can be so diverse when comparing competing synthesis routes (e.g. solution versus vapour growth) that we should not be surprised if different crystallographic phases with different morphologies are obtained, even if metastable. We should not forget here that the amazingly large number of available molecules is due to the longstanding and innovative work of synthesis chemists, a task that has not been sufficiently recognized (laymen in the domain of synthesis of organic molecules tend to believe that almost any molecule can be synthesized). In summary, one of the goals of this issue is to highlight the emerging importance of the field of thin molecular organic films by giving selected examples. It is clear that some important examples are missing, which are due in part to space limitation and to the understandable reluctance of highly-ranked specialists to contribute because of work overload. Among these not included but not forgotten subjects we can list films showing linear and non

Fraxedas, J.

2008-03-01

226

Recording, noise, and servo characteristics of patterned thin film media  

Microsoft Academic Search

In this paper, we present a combined experimental and micromagnetic simulation study of the recording, noise and position error signal characteristics in patterned thin film media. The medium is patterned with a focused ion beam etching technique on typical present thin film disks. It is found the transition noise is completely absent in the patterned thin film media. Comparing with

Jian-Gang Zhu; Ziangdong Lin; Lijie Guan; William Messner

2000-01-01

227

THIN FILM MECHANICS BULGING AND Ph.D Dissertation  

E-print Network

THIN FILM MECHANICS ­BULGING AND STRETCHING Ph.D Dissertation Mechanical Engineering University of Vermont Wolfgang Sauter October 2000 #12;ii Abstract Thin films have experienced revolutionary development for the intensive effort in research in materials and processing techniques. Thin film windows are window

Huston, Dryver R.

228

Unabridged phase diagram for single-phased FeSexTe1-x thin films  

NASA Astrophysics Data System (ADS)

A complete phase diagram and its corresponding physical properties are essential prerequisites to understand the underlying mechanism of iron-based superconductivity. For the structurally simplest 11 (FeSeTe) system, earlier attempts using bulk samples have not been able to do so due to the fabrication difficulties. Here, thin FeSexTe1-x films with the Se content covering the full range (0 <= x <= 1) were fabricated by using pulsed laser deposition method. Crystal structure analysis shows that all films retain the tetragonal structure in room temperature. Significantly, the highest superconducting transition temperature (TC = 20 K) occurs in the newly discovered domain, i.e., 0.6 <= x <= 0.8. The single-phased superconducting dome for the full Se doping range is the first of its kind in iron chalcogenide superconductors. Our results present a new avenue to explore novel physics as well as to optimize superconductors.

Zhuang, Jincheng; Yeoh, Wai Kong; Cui, Xiangyuan; Xu, Xun; Du, Yi; Shi, Zhixiang; Ringer, Simon P.; Wang, Xiaolin; Dou, Shi Xue

2014-12-01

229

Unabridged phase diagram for single-phased FeSe(x)Te(1-x) thin films.  

PubMed

A complete phase diagram and its corresponding physical properties are essential prerequisites to understand the underlying mechanism of iron-based superconductivity. For the structurally simplest 11 (FeSeTe) system, earlier attempts using bulk samples have not been able to do so due to the fabrication difficulties. Here, thin FeSe(x)Te(1-x) films with the Se content covering the full range (0 ? x ? 1) were fabricated by using pulsed laser deposition method. Crystal structure analysis shows that all films retain the tetragonal structure in room temperature. Significantly, the highest superconducting transition temperature (T(C) = 20 K) occurs in the newly discovered domain, i.e., 0.6 ? x ? 0.8. The single-phased superconducting dome for the full Se doping range is the first of its kind in iron chalcogenide superconductors. Our results present a new avenue to explore novel physics as well as to optimize superconductors. PMID:25449669

Zhuang, Jincheng; Yeoh, Wai Kong; Cui, Xiangyuan; Xu, Xun; Du, Yi; Shi, Zhixiang; Ringer, Simon P; Wang, Xiaolin; Dou, Shi Xue

2014-01-01

230

Aspects of passive magnetic levitation based on high-T(sub c) superconducting YBCO thin films  

NASA Technical Reports Server (NTRS)

Passive magnetic levitation systems reported in the past were mostly confined to bulk superconducting materials. Here we present fundamental studies on magnetic levitation employing cylindrical permanent magnets floating above high-T(sub c) superconducting YBCO thin films (thickness about 0.3 mu m). Experiments included free floating rotating magnets as well as well-established flexible beam methods. By means of the latter, we investigated levitation and drag force hysteresis as well as magnetic stiffness properties of the superconductor-magnet arrangement. In the case of vertical motion of the magnet, characteristic high symmetry of repulsive (approaching) and attractive (withdrawing) branches of the pronounced force-displacement hysteresis could be detected. Achievable force levels were low as expected but sufficient for levitation of permanent magnets. With regard to magnetic stiffness, thin films proved to show stiffness-force ratios about one order of magnitude higher than bulk materials. Phenomenological models support the measurements. Regarding the magnetic hysteresis of the superconductor, the Irie-Yamafuji model was used for solving the equation of force balance in cylindrical coordinates allowing for a macroscopic description of the superconductor magnetization. This procedure provided good agreement with experimental levitation force and stiffness data during vertical motion. For the case of (lateral) drag force basic qualitative characteristics could be recovered, too. It is shown that models, based on simple asymmetric magnetization of the superconductor, describe well asymptotic transition of drag forces after the change of the magnet motion direction. Virgin curves (starting from equilibrium, i.e. symmetric magnetization) are approximated by a linear approach already reported in literature only. This paper shows that basic properties of superconducting thin films allow for their application to magnetic levitation or - without need of levitation forces, e.g. microgravity - magnetic damping devices.

Schoenhuber, P.; Moon, F. C.

1995-01-01

231

Vortex states at T=0 in disordered thin and thick films of a-Mo xSi 1- x  

NASA Astrophysics Data System (ADS)

We measure the transport properties of highly disordered thin and thick films of amorphous (a-)Mo xSi 1- x at low temperatures T. For thin films we have observed an anomalous peak in the magnetoresistance in fields B higher than the critical field BC of the field-driven superconductor-insulator transition (SIT). This suggests the presence of localized Cooper pairs on the insulating side of the SIT. We present data supporting the view that this insulating regime may correspond to the quantum-vortex-liquid (QVL) phase. The metallic QVL phase in B< BC is not evident, most likely absent. On the other hand, for thick films the existence of the vortex-glass transition and the metallic QVL phase at T=0 has been demonstrated. Based on these data, we construct the T=0 phase diagram of disordered two-dimensional and three-dimensional superconductors.

Morita, M.; Okuma, S.

2001-11-01

232

Physical aging of thin glassy polymer films  

NASA Astrophysics Data System (ADS)

This research work was designed to systematically investigate the physical aging of glassy polymer thin films in terms of the effects of chemical structure of the polymer, film thickness, aging temperature and molecular weight. This research is fundamental in nature but is of both scientific interest and practical importance, especially to gas separation industry where polymer thin films are essentially used as the selective layer in the asymmetric or composite membrane structures. Three glassy polymers relevant to gas separation industry, polysulfone, a polyimide and poly(2,6-dimethyl-1,4-phenylene oxide) were studied; these polymer films having thicknesses from ˜ 400 nm to 62 mum were subjected to isothermal aging at three temperatures, ranging from 35 to 55°C, for a period of up to ˜ 400 days. Two major techniques were employed in probing the aging process including gas permeability measurement and refractive index measurement. Rigorous methodologies have been developed for studying the physical aging of free-standing thin polymer films to eliminate any other external effect that might impact the aging behavior. Ellipsometry has been employed to determine the thicknesses and refractive indices of these thin films. By using the methods developed, the reproducibility of gas permeability and refractive index change during physical aging was demonstrated as well as the thermoreversibility of physical aging. Ellipsometry revealed that this procedure leads to isotropic films having initial characteristics independent of film thickness. A substantial aging response via the permeability and refractive index changes, attributed to a decrease in polymer free volume, was observed at temperatures more than 150°C below Tg for thin films of each polymer compared to what is observed for the bulk polymers. The Lorenz-Lorenz equation was used to relate changes in refractive index to densification, or volume relaxation, with aging time. The films with thicknesses of approximately 400 nm of the three polymers exhibit an oxygen permeability decrease by as much as two-fold or more, about 14 to 15% increase in O 2/N2 selectivity and about 0.6 to 1.5% increase in density at an aging time of 1,000 hours. (Abstract shortened by UMI.)

Huang, Yu

233

Pulsed laser deposition of nasicon thin films  

NASA Astrophysics Data System (ADS)

We have deposited NASICON ( Na Super Ionic CONductor) films of thicknesses ranging from 100 to 600 nm, by Pulsed Laser Deposition (PLD), on SiO 2/Si substrates. The deposition rates varied from 6 × 10 -3 to 0.08 nm/pulse depending on the conditions employed. XPS measurements show that all elements are transferred from the target to the substrate and that the thin film composition is very close to that of the target. Film morphology depends upon the laser energy density at the target. Films deposited at about 2 J/cm 2 show a rough surface and a columnar structure. At lower energy density (400 mj/cm 2), a smoother surface is obtained. Electrical measurements show good ionic conductivity, and that the films are suitable for the fabrication of electrochemical gas sensors.

Izquierdo, R.; Hanus, F.; Lang, Th.; Ivanov, D.; Meunier, M.; Laude, L.; Currie, J. F.; Yelon, A.

1996-04-01

234

Semiconductor cooling by thin-film thermocouples  

NASA Technical Reports Server (NTRS)

Thin-film, metal alloy thermocouple junctions do not rectify, change circuit impedance only slightly, and require very little increase in space. Although they are less efficient cooling devices than semiconductor junctions, they may be applied to assist conventional cooling techniques for electronic devices.

Tick, P. A.; Vilcans, J.

1970-01-01

235

The optical properties of YBCO thin films  

Microsoft Academic Search

We present strong evidence that there is no specific mid- infrared absorption band in YBCO and a generalised Drude model can be used to explain all of the observed features in the optical spectrum. A high vacuum, low temperature ATR experiment has been used to excite surface plasmons (SPP) on YBCO thin films at different temperatures. We have found that

Roger James Wallace

1997-01-01

236

Synthesis of thin molecular sieve films  

Microsoft Academic Search

A method to synthesize thin films of various molecular sieves on a number of substrates employing pre-seeding has been developed. The substrate is modified to enable adsorption of seed crystals. Substrates with an originally negative surface charge are charge reversed by adsorption of cationic polymer molecules. Nobel metal substrates are first silanized to obtain a negative surface charge. Nano seed

J. Hedlund; J. Sterte

1999-01-01

237

Microwave-enhanced thin-film deposition  

NASA Technical Reports Server (NTRS)

The deposition of semiconducting and insulating thin films at low temperatures using microwave technology was explored. The method of plasma formations, selection of a power source, the design of the microwave plasma cavity, the microwave circuitry, impedance matching, plasma diagnostics, the deposition chamber and the vacuum system were studied.

Chitre, S.

1984-01-01

238

Thin film hydrous metal oxide catalysts  

DOEpatents

Thin film (<100 nm) hydrous metal oxide catalysts are prepared by 1) synthesis of a hydrous metal oxide, 2) deposition of the hydrous metal oxide upon an inert support surface, 3) ion exchange with catalytically active metals, and 4) activating the hydrous metal oxide catalysts.

Dosch, Robert G. (Albuquerque, NM); Stephens, Howard P. (Albuquerque, NM)

1995-01-01

239

Nanostructured Stable Thin Polymer Films (DMR-0819860)  

E-print Network

Nanostructured Stable Thin Polymer Films (DMR-0819860) SEED: R. D. Priestley and C.B. Arnold. The image (right) illustrates the stability of the nanostructured morphology, against coalescence, at temperatures well above the normal Tg of 350 K. In addition, the nanostructured morphology is formed during

Petta, Jason

240

ORIGINAL PAPER Nanocrystalline Diamond Thin Films Synthesis  

E-print Network

. Qin · Dunwen Zuo · R. W. Boswell · Wenzhuang Lu · Zbigniew Stachurski Received: 10 October 2013-mail: ldsnuaa@nuaa.edu.cn D. Li Á Q. H. Qin Á Z. Stachurski Research School of Engineering, Australian National no report of growing CS-NCD thin film on non-spherical surface molybdenum (Mo) substrate. Huang and Lunn [16

Qin, Qinghua

241

Thin film thermocouples for internal combustion engines  

Microsoft Academic Search

The feasibility of fabricating thin film thermocouples on internal combustion engine hardware was investigated. The goal was to find a procedure that would be useful for the measurement of the surface metal temperature of valves, valve seats, combustion chamber surfaces, cylinder walls, and piston heads during engine operation. The approach pursued was to coat the engine hardware material with an

Kenneth G. Kreider

1986-01-01

242

Thin-Film Solid Oxide Fuel Cells  

NASA Technical Reports Server (NTRS)

The development of thin-film solid oxide fuel cells (TFSOFCs) and a method of fabricating them have progressed to the prototype stage. This can result in the reduction of mass, volume, and the cost of materials for a given power level.

Chen, Xin; Wu, Nai-Juan; Ignatiev, Alex

2009-01-01

243

Analysis of hydrogen isotopes in thin films  

Microsoft Academic Search

Mass spectrometer modifications made for high resolution analysis of hydrogen isotopes outgassed from occluder thin films are described. The electronic modifications made to the source, magnet power supply, and scanning circuits provided increased precision in the mass range 2 to 6. Routine analyses were made at a resolution of 1300 with a Faraday cup detector. Extensive modification of the inlet

T. K. Mehrhoff; J. O. Humphries

1976-01-01

244

Laser Forming of Thin Film Metallic Glass  

NASA Astrophysics Data System (ADS)

Palladium based thin film metallic glasses were plastically bent by laser forming process. Thin films of Pd77Cu6Si17 with a thickness of 0.028mm and Pd40Ni40P20 with a thickness of 0.017mm were used for specimen. A 50W YAG laser was employed for forming. Variation of bending angle was investigated by changing working conditions such as laser power, laser operation mode (continuous wave and Q-switch pulsed modes), Q-sw frequency, scanning velocity and scanning number. From the experimental results, both thin films of Pd77Cu6Si17 and Pd40Ni40P20 were successfully bent for more than 85°. The formed thin films did not crystallize but were amorphous. As scanning number increased, bending angle also increased but increasing rate decreased. When laser power and scanning velocity were changed, bending angle had a peak. When Q-sw frequency was changed, bending angle had a broad peak in Pd77Cu6Si17 case, but that was larger as frequency was smaller in Pd40Ni40P20 case.

Otsu, Masaaki; Ide, Yuki; Sakurai, Junpei; Hata, Seiichi; Takashima, Kazuki

245

Flexoelectricity in barium strontium titanate thin film  

NASA Astrophysics Data System (ADS)

Flexoelectricity, the linear coupling between the strain gradient and the induced electric polarization, has been intensively studied as an alternative to piezoelectricity. Especially, it is of interest to develop flexoelectric devices on micro/nano scales due to the inherent scaling effect of flexoelectric effect. Ba0.7Sr0.3TiO3 thin film with a thickness of 130 nm was fabricated on a silicon wafer using a RF magnetron sputtering process. The flexoelectric coefficients of the prepared thin films were determined experimentally. It was revealed that the thin films possessed a transverse flexoelectric coefficient of 24.5 ?C/m at Curie temperature (˜28 °C) and 17.44 ?C/m at 41 °C. The measured flexoelectric coefficients are comparable to that of bulk BST ceramics, which are reported to be 10-100 ?C/m. This result suggests that the flexoelectric thin film structures can be effectively used for micro/nano-sensing devices.

Kwon, Seol Ryung; Huang, Wenbin; Shu, Longlong; Yuan, Fuh-Gwo; Maria, Jon-Paul; Jiang, Xiaoning

2014-10-01

246

Structuring of thin film solar cells  

Microsoft Academic Search

Laser structuring of different types of thin film layers is a state of the art process in the photovoltaic industry. TCO layers and molybdenum are structured with e.g. 1064 nm lasers. Amorphous silicon, microcrystalline silicon or cadmium telluride are ablated with 515\\/532 nm lasers. Typical pulse durations of the lasers in use for these material ablation processes are in the

Gabriele Eberhardt; Henrik Banse; Uwe Wagner; Thomas Peschel

2010-01-01

247

Gravitationally driven drainage of thin films  

NASA Astrophysics Data System (ADS)

In this thesis we develop theory for an experiment done by Snow and coworkers at Dow Corning that involves a vertically-oriented, thinned polyurethane film with silicone surfactant, draining under gravity. We present the mathematical formulation for a 1+1- and 2+1-dimensional model to study the evolution of a vertically-oriented thin liquid film draining under gravity when there is an insoluble surfactant with finite surface viscosity on its free surface. This formulation has all the ingredients that include: surface tension, gravity, surface viscosity, the Marangoni effect, convective and diffusive surfactant transport; essential to describe the behavior of a vertical draining film with surfactant. We study a hierarchy of mathematical models with increasing complexity starting with the flat film model where gravity balances viscous shear and surface tension is neglected, this is generalized to include surface tension. We further generalize to incorporate variable surface viscosity and more complicated constitutive laws for surface tension as a function of surfactant concentration. Lubrication theory is employed to derive three coupled nonlinear partial differential equations (PDEs) describing the free surface shape, a component of surface velocity and the surfactant transport at leading order. A large surface viscosity limit recovers the tangentially-immobile model; for small surface viscosity, the film is mobile. Transition from a mobile to an immobile film is observed for intermediate values of surface viscosity and Marangoni number. The above models reproduce a number of features observed in experiments, these include film shapes and thinning rates which can be correlated to experiment. The 2+1-dimensional model for simplified surface properties has also been studied. Numerical experiments were performed to understand the stability of the system to perturbations across the film. An instability was seen in the mobile case; this was caused by a competition between gravity and the Marangoni effect. The behavior observed from this model qualitatively matches the structures observed in Dow Corning experiments; more work is needed to compare our numerics with experiment quantitatively.

Naire, Shailesh

248

A magnetron sputtering system for the preparation of patterned thin films and in situ thin film electrical resistance measurements  

SciTech Connect

We describe a versatile three gun magnetron sputtering system with a custom made sample holder for in situ electrical resistance measurements, both during film growth and ambient changes on film electrical properties. The sample holder allows for the preparation of patterned thin film structures, using up to five different shadow masks without breaking vacuum. We show how the system is used to monitor the electrical resistance of thin metallic films during growth and to study the thermodynamics of hydrogen uptake in metallic thin films. Furthermore, we demonstrate the growth of thin film capacitors, where patterned films are created using shadow masks.

Arnalds, U. B.; Agustsson, J. S.; Ingason, A. S.; Eriksson, A. K.; Gylfason, K. B.; Gudmundsson, J. T.; Olafsson, S. [Matvice, Dunhaga 3, IS-107 Reykjavik (Iceland); Mentis Cura ehf., Grandagardi 7, IS-107 Reykjavik (Iceland); Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); Microsystem Technology Laboratory, School of Electrical Engineering, KTH-Royal Institute of Technology, SE-100 44 Stockholm (Sweden); Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland) and Department of Electrical and Computer Engineering, University of Iceland, Hjardarhaga 2-6, IS-107 Reykjavik (Iceland); Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland)

2007-10-15

249

Electrolyte and Electrode Passivation for Thin Film Batteries  

NASA Technical Reports Server (NTRS)

Passivation films for thin film batteries have been prepared and the conductivity and voltage stability window have been measured. Thin films of Li2CO3 have a large voltage stability window of 4.8V, which facilitates the use of this film as a passivation at both the lithium anode-electrolyte interface at high cathodic potentials.

West, W.; Whitacre, J.; Ratnakumar, B.; Brandon, E.; Blosiu, J.; Surampudi, S.

2000-01-01

250

WO 3 sputtered thin films for NO x monitoring  

Microsoft Academic Search

We present in this paper preliminary results concerning the preparation of tungsten trioxide thin films by reactive sputtering, the characterization either of their structural properties by means of XRD measurements or of the film morphology with the AFM microscope and the electrical response of the film towards toxic and pollutant gases. WO3 thin films showed a good sensitivity towards low

G. Sberveglieri; L. Depero; S. Groppelli; P. Nelli

1995-01-01

251

Microsecond minority carrier lifetimes in HWCVD-grown films and implications for thin film solar cells  

E-print Network

-wire deposition; Silicon; Photoconductive decay; Photovoltaics 1. Introduction We propose the design for thin filmMicrosecond minority carrier lifetimes in HWCVD-grown films and implications for thin film solar design for thin-film photovoltaics. D 2005 Elsevier B.V. All rights reserved. Keywords: Hot

Atwater, Harry

252

MISSE 5 Thin Films Space Exposure Experiment  

NASA Technical Reports Server (NTRS)

The Materials International Space Station Experiment (MISSE) is a set of space exposure experiments using the International Space Station (ISS) as the flight platform. MISSE 5 is a co-operative endeavor by NASA-LaRC, United Stated Naval Academy, Naval Center for Space Technology (NCST), NASA-GRC, NASA-MSFC, Boeing, AZ Technology, MURE, and Team Cooperative. The primary experiment is performance measurement and monitoring of high performance solar cells for U.S. Navy research and development. A secondary experiment is the telemetry of this data to ground stations. A third experiment is the measurement of low-Earth-orbit (LEO) low-Sun-exposure space effects on thin film materials. Thin films can provide extremely efficacious thermal control, designation, and propulsion functions in space to name a few applications. Solar ultraviolet radiation and atomic oxygen are major degradation mechanisms in LEO. This paper is an engineering report of the MISSE 5 thm films 13 months space exposure experiment.

Harvey, Gale A.; Kinard, William H.; Jones, James L.

2007-01-01

253

Thin film multiferroic nanocomposites by ion implantation.  

PubMed

Thin film multiferroic nanocomposites might enable a range of potentially disruptive integrated magnetoelectric devices for information storage, spintronics, microwave telecommunications, and magnetic sensing. With this aim, we have investigated ion implantation of magnetic species into ferroelectric single crystal targets as a radically novel approach to prepare film nanoparticulate magnetic-metal ferroelectric-oxide composites. These materials are an alternative to multiferroic oxide epitaxial columnar nanostructures that are under intensive research, but whose magnetoelectric response is far from expectations. Here, we unambiguously demonstrate the preparation of such a thin film multiferroic nanocomposite of Co and BaTiO3 by ion implantation of a high dose of the magnetic species, followed by rapid thermal processing under tailored conditions. Results thus constitute a proof of concept for the feasibility of obtaining the materials by this alternative approach. Ion implantation is a standard technique for the microelectronic industry in combination with well-established patterning procedures. PMID:24417708

Algueró, Miguel; Ricote, Jesús; Torres, María; Amorín, Harvey; Alberca, Aurora; Iglesias-Freire, Oscar; Nemes, Norbert; Holgado, Susana; Cervera, Manuel; Piqueras, Juan; Asenjo, Agustina; García-Hernández, Mar

2014-02-12

254

Nanoindentation of GaSe thin films  

PubMed Central

The structural and nanomechanical properties of GaSe thin films were investigated by means of X-ray diffraction (XRD) and nanoindentation techniques. The GaSe thin films were deposited on Si(111) substrates by pulsed laser deposition. XRD patterns reveal only the pure (000?l)-oriented reflections originating from the hexagonal GaSe phase and no trace of any impurity or additional phases. Nanoindentation results exhibit discontinuities (so-called multiple ‘pop-in’ events) in the loading segments of the load–displacement curves, and the continuous stiffness measurements indicate that the hardness and Young’s modulus of the hexagonal GaSe films are 1.8?±?0.2 and 65.8?±?5.6?GPa, respectively. PMID:22804961

2012-01-01

255

Photoacoustic elastic bending in thin film-substrate system: Experimental determination of the thin film parameters  

NASA Astrophysics Data System (ADS)

The aim of this work is the development of photoacoustic (PA) method for the measurement and determination of parametres of thin films (with a thickness of less than 1 ?m). Experimental study of the optical, thermal, and elastic characteristics of the thin film on Si substrate by PA elastic bending method was given. Thin film-semiconductor (Si) sample is modeled by simultaneous analysis of the plasma, thermal, and elastic wave equations. Two normalization procedures of the PA elastic bending signal in function of the modulation frequency of the optical excitation were established. The experimental PA elastic bending signals were measured and analysed. Without loss of generality, the TiO2 thin film (with a thickness of 0.5 ?m) on Si substrate (circular plate) was experimentaly studied. We have studied the PA elastic bending signals in order to obtain the values of optical, thermal, and elastic parameters of TiO2 film. The analysis shows that it is possible to develop noncontact and nondestructive experimental method—PA elastic bending method for thin film study, with possibility to obtain the optical, thermal, and elastic parameters of the film thinner than 1 ?m.

Todorovi?, D. M.; Rabasovi?, M. D.; Markushev, D. D.; Sarajli?, M.

2014-08-01

256

Magnon dispersion in thin magnetic films  

NASA Astrophysics Data System (ADS)

Although the dispersion of magnons has been measured in many bulk materials, few studies deal with the changes in the dispersion when the material is in the form of a thin film, a system that is of interest for applications. Here we review inelastic tunneling spectroscopy studies of magnon dispersion in Mn/Cu3Au(1?0?0) and present new studies on Co and Ni thin films on Cu(1?0?0). The dispersion in Mn and Co films closely follows the dispersion of bulk samples with negligible dependence on thickness. The lifetime of magnons depends slightly on film thickness, and decreases considerably as the magnon energy increases. In Ni/Cu(1?0?0) films the thickness dependence of dispersion is much more pronounced. The measurements indicate a considerable mode softening for thinner films. Magnon lifetimes decrease dramatically near the edge of the Brillouin zone due to a close proximity of the Stoner continuum. The experimental study is supported by first-principles calculations.

Balashov, T.; Buczek, P.; Sandratskii, L.; Ernst, A.; Wulfhekel, W.

2014-10-01

257

Diamond magnetometry of superconducting thin films  

NASA Astrophysics Data System (ADS)

In recent years, diamond magnetometers based on the nitrogen-vacancy (NV) center have been of considerable interest for applications at the nanoscale. An interesting application which is well suited for NV centers is the study of nanoscale magnetic phenomena in superconducting materials. We employ NV centers to interrogate magnetic properties of a thin-layer yttrium barium copper oxide (YBCO) superconductor. Using fluorescence-microscopy methods and samples integrated with an NV sensor on a microchip, we measure the temperature of phase transition in the layer to be 70.0(2) K and the penetration field of vortices to be 46(4) G. We observe pinning of the vortices in the layer at 65 K and estimate their density after cooling the sample in a ˜10-G field to be 0.45(1) ?m-2. These measurements are done with a 10-nm-thick NV layer, so that high spatial resolution may be enabled in the future. Based on these results, we anticipate that this magnetometer could be useful for imaging the structure and dynamics of vortices. As an outlook, we present a fabrication method for a superconductor chip designed for this purpose.

Waxman, A.; Schlussel, Y.; Groswasser, D.; Acosta, V. M.; Bouchard, L.-S.; Budker, D.; Folman, R.

2014-02-01

258

Doping in zinc oxide thin films  

NASA Astrophysics Data System (ADS)

Doping in zinc oxide (ZnO) thin films is discussed in this dissertation. The optimizations of undoped ZnO thin film growth using molecular-beam epitaxy (MBE) are discussed. The effect of the oxygen ECR plasma power on the growth rate, structural, electrical, and optical properties of the ZnO thin films were studied. It was found that larger ECR power leads to higher growth rate, better crystallinity, lower electron carrier concentration, larger resistivity, and smaller density of non-radiative luminescence centers in the ZnO thin films. Low-temperature photoluminescence (PL) measurements were carried out in undoped and Ga-doped ZnO thin films grown by molecular-beam epitaxy. As the carrier concentration increases from 1.8 x 1018 to 1.8 x 1020 cm-3, the dominant PL line at 9 K changes from I1 (3.368--3.371 eV), to IDA (3.317--3.321 eV), and finally to I8 (3.359 eV). The dominance of I1, due to ionized-donor bound excitons, is unexpected in n-type samples, but is shown to be consistent with the temperature-dependent Hall fitting results. We also show that IDA has characteristics of a donor-acceptor-pair transition, and use a detailed, quantitative analysis to argue that it arises from GaZn donors paired with Zn-vacancy (VZn) acceptors. In this analysis, the GaZn0/+ energy is well-known from two-electron satellite transitions, and the VZn0/- energy is taken from a recent theoretical calculation. Typical behaviors of Sb-doped p-type ZnO are presented. The Sb doping mechanisms and preference in ZnO are discussed. Diluted magnetic semiconducting ZnO:Co thin films with above room-temperature TC were prepared. Transmission electron microscopy and x-ray diffraction studies indicate the ZnO:Co thin films are free of secondary phases. The magnetization of the ZnO:Co thin films shows a free electron carrier concentration dependence, which increases dramatically when the free electron carrier concentration exceeds ˜1019 cm -3, indicating a carrier-mediated mechanism for ferromagnetism. The anomalous Hall effect was observed in the ZnO:Co thin films. The anomalous Hall coefficient and its dependence on longitudinal resistivity were analyzed. The presence of a side-jump contribution further supports an intrinsic origin for ferromagnetism in ZnO:Co thin films. These observations together with the magnetic anisotropy and magnetoresistance results, supports an intrinsic carrier-mediated mechanism for ferromagnetic exchange in ZnO:Co diluted magnetic semiconductor materials. Well-above room temperature and electron-concentration dependent ferromagnetism was observed in n-type ZnO:Mn films, indicating long-range ferromagnetic order. Magnetic anisotropy was also observed in these ZnO:Mn films, which is another indication for intrinsic ferromagnetism. The electron-mediated ferromagnetism in n-type ZnO:Mn contradicts the existing theory that the magnetic exchange in ZnO:Mn materials is mediated by holes. Microstructural studies using transmission electron microscopy were performed on a ZnO:Mn diluted magnetic semiconductor thin film. The high-resolution imaging and electron diffraction reveal that the ZnO:Mn thin film has a high structual quality and is free of clustering/segregated phases. High-angle annular dark field imaging and x-ray diffraction patterns further support the absence of phase segregation in the film. Magnetotransport was studied on the ZnO:Mn samples, and from these measurements, the temperature dependence of the resistivity and magnetoresistance, electron carrier concentration, and anomalous Hall coefficient of the sample is discussed. The anomalous Hall coefficient depends on the resistivity, and from this relation, the presence of the quadratic dependence term supports the intrinsic spin-obit origin of the anomalous Hall effect in the ZnO:Mn thin film.

Yang, Zheng

259

Fabrication and characterization of amorphous lithium electrolyte thin films and rechargeable thin-film batteries  

Microsoft Academic Search

Amorphous oxide and oxynitride lithium electrolyte thin films were synthesized by r.f. magnetron sputtering of lithium silicates and lithium phosphates in Ar, Ar + O2, Ar + N2, or N2. The composition, structure, and electrical properties of the films were characterized using ion and electron beam, X ray, optical, photoelectron, and a.c. impedance techniques. For the lithium phosphosilicate films, lithium

J. B. Bates; N. J. Dudney; G. R. Gruzalski; R. A. Zuhr; A. Choudhury; C. F. Luck; J. D. Robertson

1993-01-01

260

A Multilayered Thin Film Insulator for Harsh Environments  

NASA Technical Reports Server (NTRS)

The status of work to develop a reliable high temperature dielectric thin film for use with thin film sensors is presented. The use of thin films to electrically insulate thin film sensors on engine components minimizes the intrusiveness of the sensor and allows a more accurate measurement of the environment. A variety of insulating films were investigated for preventing electrical shorting caused by insulator failure between the sensor and the component. By alternating layers of sputtered high temperature ceramics, a sequence of insulating layers was devised that prevents pinholes from forming completely through the insulator and maintains high electrical resistivity at high temperatures. The major technical challenge remaining is to optimize the fabrication of the insulator with respect to composition to achieve a reliable high temperature insulating film. Data from the testing of various potentially insulating thin film systems is presented and their application to thin film sensors is also discussed.

Wrbanek, John D.; Fralick, Gustave C.; Blaha, Charles A.; Busfield, A. Rachel; Thomas, Valarie D.

2002-01-01

261

Polycrystalline thin film materials and devices  

SciTech Connect

Results of Phase II of a research program on polycrystalline thin film heterojunction solar cells are presented. Relations between processing, materials properties and device performance were studied. The analysis of these solar cells explains how minority carrier recombination at the interface and at grain boundaries can be reduced by doping of windows and absorber layers, such as in high efficiency CdTe and CuInSe{sub 2} based solar cells. The additional geometric dimension introduced by the polycrystallinity must be taken into consideration. The solar cells are limited by the diode current, caused by recombination in the space charge region. J-V characteristics of CuInSe{sub 2}/(CdZn)S cells were analyzed. Current-voltage and spectral response measurements were also made on high efficiency CdTe/CdS thin film solar cells prepared by vacuum evaporation. Cu-In bilayers were reacted with Se and H{sub 2}Se gas to form CuInSe{sub 2} films; the reaction pathways and the precursor were studied. Several approaches to fabrication of these thin film solar cells in a superstrate configuration were explored. A self-consistent picture of the effects of processing on the evolution of CdTe cells was developed.

Baron, B.N.; Birkmire, R.W.; Phillips, J.E.; Shafarman, W.N.; Hegedus, S.S.; McCandless, B.E. (Delaware Univ., Newark, DE (United States). Inst. of Energy Conversion)

1992-10-01

262

Photoelectrochemical activity of titanium dioxide thin films  

NASA Astrophysics Data System (ADS)

Crystalline titanium dioxide (TiO2) thin films have been extensively investigated due to their various applications in a wide range of field such as photocatalysis, solar cells, gas sensors, self-cleaning windows, etc. The general objective of the present work can be categorized into two different parts. The first part of research is to acquire a fundamental understanding of thin film deposition and characterization of materials surfaces produced by Electrolytic Plasma Processing (EPP) and Magnetron Sputtering system. It has been tried to develop a crystalline layer of titanium dioxide thin film using these two techniques. Aluminum and titanium are the substrate materials. Also a part of study is to clean and roughen the substrate prior to the deposition to examine the effect of morphology. Aluminum was chosen as the substrate as well as titanium in order to enable us to get cheaper product. Second main portion of this work is to check the photoelectrochemical response of the deposited film and explore the effect of various parameters of coating process on this photoelectrochemical response.

Mehdinezhad Roshan, Aida

263

Thin uranium dioxide films with embedded xenon  

NASA Astrophysics Data System (ADS)

The ion beam assisted deposition (IBAD) method was applied as a means to incorporate Xe atoms into UO2 films to fabricate reference samples that are representative of an irradiated nuclear fuel without an actual reactor irradiation. The characterization of Xe content and the films microstructure was performed using Rutherford backscattering spectroscopy (RBS), atomic force microscopy (AFM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDXS). A set of UO2 films with excellent control of Xe content ranging from ˜1.0 to 4.0 at.% was fabricated. The thin UO2 films deposited on single crystalline 4H-SiC substrates were found to be composed primarily of randomly oriented nanocrystalline grains and a small fraction of amorphous material. TEM analysis detected no Xe-filled bubbles at a scale of 2.5 nm or larger.

Usov, I. O.; Dickerson, R. M.; Dickerson, P. O.; Hawley, M. E.; Byler, D. D.; McClellan, K. J.

2013-06-01

264

Polarization properties of thin films of diamond  

NASA Astrophysics Data System (ADS)

Thin films transparent to optical radiation offer polarization properties that are enhanced when the thickness of the film is an odd multiple of the quarter-wavelength. The transmission and reflection properties of a 1.16- mu m-thick film of diamond realized by plasma-assisted chemical vapor deposition have been studied at 10.6 mu m. A compact polarizer built with four films at a Brewster angle revealed an extinction ratio of better than 1:1000 of the S polarization. The interest in optics in which parasitic-reflected or transmitted beams do not exist is pointed out. The high damage threshold of diamonds opens the possibility of controlling the polarization characteristics of high-power lasers used, for example, for soldering and cutting applications.

Chardonnet, C.; Bernard, V.; Daussy, C.; Gicquel, A.; Anger, E.

1996-12-01

265

Cathodoluminescence degradation of PLD thin films  

NASA Astrophysics Data System (ADS)

The cathodoluminescence (CL) intensities of Y2SiO5:Ce3+, Gd2O2S:Tb3+ and SrAl2O4:Eu2+,Dy3+ phosphor thin films that were grown by pulsed laser deposition (PLD) were investigated for possible application in low voltage field emission displays (FEDs) and other infrastructure applications. Several process parameters (background gas, laser fluence, base pressure, substrate temperature, etc.) were changed during the deposition of the thin films. Atomic force microscopy (AFM) was used to determine the surface roughness and particle size of the different films. The layers consist of agglomerated nanoparticle structures. Samples with good light emission were selected for the electron degradation studies. Auger electron spectroscopy (AES) and CL spectroscopy were used to monitor changes in the surface chemical composition and luminous efficiency of the thin films. AES and CL spectroscopy were done with 2 keV energy electrons. Measurements were done at 1×10-6 Torr oxygen pressure. The formation of different oxide layers during electron bombardment was confirmed with X-ray photoelectron spectroscopy (XPS). New non-luminescent layers that formed during electron bombardment were responsible for the degradation in light intensity. The adventitious C was removed from the surface in all three cases as volatile gas species, which is consistent with the electron stimulated surface chemical reaction (ESSCR) model. For Y2SiO5:Ce3+ a luminescent SiO2 layer formed during the electron bombardment. Gd2O3 and SrO thin films formed on the surfaces of Gd2O2S:Tb3+ and SrAl2O4:Eu2+,Dy3+, respectively, due to ESSCRs.

Swart, H. C.; Coetsee, E.; Terblans, J. J.; Ntwaeaborwa, O. M.; Nsimama, P. D.; Dejene, F. B.; Dolo, J. J.

2010-12-01

266

Solid state thin-film lithium battery systems  

Microsoft Academic Search

Thin-film rechargeable lithium batteries, less than 15 ?m thick, are being developed as micro-power sources. Batteries with long cycle lives have been constructed with a variety of electrode materials and cell configurations onto thin ceramic, metal, and Si substrates. Improvements in the properties of several well-known cathode thin-film materials have been reported, while several novel thin-film anode materials have been

N. J. Dudney; B. J. Neudecker

1999-01-01

267

Resonant X-Ray Scattering in Block Copolymer Thin Films  

Microsoft Academic Search

Resonant x-ray scattering in a transmission geometry is reported in block copolymer films for the first time. By tuning soft x-rays to the carbon pi*-pi* bonds in a poly(styrene-b-isoprene) (PS-PI) diblock copolymer thin film, the scattering intensity is enhanced, thereby overcoming the small scattering volume inherent to a thin film geometry. This technique provides an alternative polymer thin film characterization

Justin Virgili; Jeffrey Kortright; Nitash Balsara; Rachel Segalman

2006-01-01

268

Pb-based ferroelectric thin film actuator for optical applications  

Microsoft Academic Search

Novel PZT thin film actuators for optical applications were proposed. Key issues for realizing the actuators such as PZT thin\\u000a film processes, mechanical properties evaluation of thin films, and design for laminated structure were described. [1 1 1]-oriented\\u000a PZT films were obtained by anneal\\/non-anneal sputtering process. Also for PZT dry etching, it was made clear low pressure\\u000a and low temperature

M. Sakata; S. Wakabayashi; M. Ikeda; H. Goto; M. Takeuchi; T. Yada

1995-01-01

269

Thermal conductivities of thin, sputtered optical films  

SciTech Connect

The normal component of the thin film thermal conductivity has been measured for the first time for several advanced sputtered optical materials. Included are data for single layers of boron nitride (BN), aluminum nitride (AIN), silicon aluminum nitride (Si-Al-N), silicon aluminum oxynitride (Si-Al-O-N), silicon carbide (SiC), and for dielectric-enhanced metal reflectors of the form Al(SiO{sub 2}/Si{sub 3}N{sub 4}){sup n} and Al(Al{sub 2}O{sub 3}/AIN){sup n}. Sputtered films of more conventional materials like SiO{sub 2}, Al{sub 2}O{sub 3}, Ta{sub 2}O{sub 5}, Ti, and Si have also been measured. The data show that thin film thermal conductivities are typically 10 to 100 times lower than conductivities for the same materials in bulk form. Structural disorder in the amorphous or very fine-grained films appears to account for most of the conductivity difference. Conclusive evidence for a film/substrate interface contribution is presented.

Henager, C.H. Jr.; Pawlewicz, W.T.

1991-05-01

270

Photoconduction in GaSe thin films  

Microsoft Academic Search

Photoconduction in GaSe thin films has been measured in the spectral energy range 1?0 eV-3?2 eV. Extrapolation of the linear region of the spectral response curve gives 1?67 eV as the energy gap of the as-grown films. Measurements have been made in the temperature- range 77 K–300 K and the activation energy for the photo-conductive processes is found to be 0?19 eV.

MOHAMMAD KHALID ANIS; MOHAMMAD YAR ZAHEER; FATEH MOHAMMAD NAZAR

1981-01-01

271

High temperature thin film strain gauges  

NASA Astrophysics Data System (ADS)

The development of thin-film resistance strain gauges suitable for dynamic stress measurements up to 900 C and intended for blade vibration measurements is reported. The strain gauge is deposited by RF sputtering on nickel-base superalloys and consists of an NiCoCrAlY coating, an Al2O3 insulating layer, a sensing layer (NiCr, PdCr), an intermediate splicing layer (Pt), and a protective film (Al2O3 or SiO2). The electrical and mechanical properties of the sensing layers and preliminary results on the thermal stability of the gauges are discussed.

Kayser, P.; Godefroy, J. C.; Leca, L.

272

Reorientation dynamics in thin glassy films  

E-print Network

We present a study of orientational relaxation dynamics in thin films of a low-molecular-weight glass-former as a function of temperature and film thickness. The relaxation is probed by second-harmonic generation after release of a poling electric field. From the measured decays of the second-harmonic signal and their fitting with a stretched exponential, we can determine the distribution of relaxation times in the system. As temperature decreases from above the glass transition, we observe that the width of the distribution first increases under confinement, but that deeper in the glassy state, confinement has no effect anymore on the dynamics.

Elio Cecchetto; Daniele Moroni; Blandine Jerome

2004-02-26

273

Microwave Absorption Studies on HIGH-Tc Superconductors and Related Materials I—LOW-FIELD Microwave Absorption in a BiSrCaCuO Thin Film Deposited by Mocvd  

NASA Astrophysics Data System (ADS)

Non-resonant microwave absorption as a function of temperature and magnetic field has been studied in a Bi-Sr-Ca-Cu-O film prepared by MOCVD. A maximum in the absorption as a function of temperature was observed at approximately 60 K. An average Josephson loop diameter of about 0.9~1.5 microns was inferred from the experimental results. The absorption was found to depend on the angle of the film plane relative to the applied field.

Sugawara, K.; Sugimoto, T.; Yasuike, K.; Baar, D. J.; Shiohara, Y.; Tanaka, S.

274

RAPID COMMUNICATION: A simple test for high Jc and low Rs superconducting thin films  

NASA Astrophysics Data System (ADS)

A simple method, fishing high-Tc superconductor thin films out of a liquid nitrogen bath by a permanent magnet (field > Hc1), due to the effect of high flux pinning, has been suggested to identify films that have high critical current density (Jc > 106 A cm-2 at 77 K) and thus a low microwave surface resistance (Rs). We have demonstrated that a Nd-Fe-B magnet, having a maximum field of ~0.5 T, could fish out Tl-1223 superconducting thin films on LSAT substrate with a thickness of ~5000 Å having Jc > 1 MA cm-2 (at 77 K) whereas it could not fish out other films with Jc < 0.1 MA cm-2 at 77 K. The fished out films exhibit Rs values 237-245 µm at 77 K and 10 GHz, which is lower than that (Rs = 317 µm) of the commercially available YBCO film at the same temperature and frequency. On the other hand, the non-fishable films show very high Rs values. This method is a very simple tool to test for high Jc and good microwave properties of large area superconducting films which would otherwise require a special and expensive tool.

Sundaresan, A.; Tanaka, Y.; Iyo, A.; Kusunoki, M.; Ohshima, S.

2003-05-01

275

Nitrogen doped zinc oxide thin film  

SciTech Connect

To summarize, polycrystalline ZnO thin films were grown by reactive sputtering. Nitrogen was introduced into the films by reactive sputtering in an NO{sub 2} plasma or by N{sup +} implantation. All ZnO films grown show n-type conductivity. In unintentionally doped ZnO films, the n-type conductivities are attributed to Zn{sub i}, a native shallow donor. In NO{sub 2}-grown ZnO films, the n-type conductivity is attributed to (N{sub 2}){sub O}, a shallow double donor. In NO{sub 2}-grown ZnO films, 0.3 atomic % nitrogen was found to exist in the form of N{sub 2}O and N{sub 2}. Upon annealing, N{sub 2}O decomposes into N{sub 2} and O{sub 2}. In furnace-annealed samples N{sub 2} redistributes diffusively and forms gaseous N{sub 2} bubbles in the films. Unintentionally doped ZnO films were grown at different oxygen partial pressures. Zni was found to form even at oxygen-rich condition and led to n-type conductivity. N{sup +} implantation into unintentionally doped ZnO film deteriorates the crystallinity and optical properties and leads to higher electron concentration. The free electrons in the implanted films are attributed to the defects introduced by implantation and formation of (N{sub 2}){sub O} and Zni. Although today there is still no reliable means to produce good quality, stable p-type ZnO material, ZnO remains an attractive material with potential for high performance short wavelength optoelectronic devices. One may argue that gallium nitride was in a similar situation a decade ago. Although we did not obtain any p-type conductivity, we hope our research will provide a valuable reference to the literature.

Li, Sonny X.

2003-12-15

276

Thin Film...Large Payoff  

NASA Technical Reports Server (NTRS)

SRS Technologies is currently the only company licensed by Langley Research Center to produce colorless polyimides. They currently produce two polyimides, the LaRC-CP1 and LaRC-CP2 developed by Langley Research Center. These polyimides offer many advantages over other commercially available materials including excellent thermal stability, radiation resistance, solubility, and transparency. The SRS polyimides can be used in laminates, films, molded parts, and stock shapes. The polyimide technology has also helped the company further their development of solar arrays.

1998-01-01

277

Stress and Moisture Effects on Thin Film Buckling Delamination  

E-print Network

films can be found in [7]. High compressive residual stress causes thin film buckling delamination high residual stresses, which can be relieved by delamination and fracture. Tungsten films with high 1 and diamond-like carbon (DLC) films. Highly stressed films store large amounts of strain energy. When

Volinsky, Alex A.

278

Polycrystalline thin films FY 1992 project report  

SciTech Connect

This report summarizes the activities and results of the Polycrystalline Thin Film Project during FY 1992. The purpose of the DOE/NREL PV (photovoltaic) Program is to facilitate the development of PV that can be used on a large enough scale to produce a significant amount of energy in the US and worldwide. The PV technologies under the Polycrystalline Thin Film project are among the most exciting ``next-generation`` options for achieving this goal. Over the last 15 years, cell-level progress has been steady, with laboratory cell efficiencies reaching levels of 15 to 16%. This progress, combined with potentially inexpensive manufacturing methods, has attracted significant commercial interest from US and international companies. The NREL/DOE program is designed to support the efforts of US companies through cost-shared subcontracts (called ``government/industry partnerships``) that we manage and fund and through collaborative technology development work among industry, universities, and our laboratory.

Zweibel, K. [ed.

1993-01-01

279

Polycrystalline thin films FY 1992 project report  

SciTech Connect

This report summarizes the activities and results of the Polycrystalline Thin Film Project during FY 1992. The purpose of the DOE/NREL PV (photovoltaic) Program is to facilitate the development of PV that can be used on a large enough scale to produce a significant amount of energy in the US and worldwide. The PV technologies under the Polycrystalline Thin Film project are among the most exciting next-generation'' options for achieving this goal. Over the last 15 years, cell-level progress has been steady, with laboratory cell efficiencies reaching levels of 15 to 16%. This progress, combined with potentially inexpensive manufacturing methods, has attracted significant commercial interest from US and international companies. The NREL/DOE program is designed to support the efforts of US companies through cost-shared subcontracts (called government/industry partnerships'') that we manage and fund and through collaborative technology development work among industry, universities, and our laboratory.

Zweibel, K. (ed.)

1993-01-01

280

Substrate heater for thin film deposition  

DOEpatents

A substrate heater for thin film deposition of metallic oxides upon a target substrate configured as a disk including means for supporting in a predetermined location a target substrate configured as a disk, means for rotating the target substrate within the support means, means for heating the target substrate within the support means, the heating means about the support means and including a pair of heating elements with one heater element situated on each side of the predetermined location for the target substrate, with one heater element defining an opening through which desired coating material can enter for thin film deposition and with the heating means including an opening slot through which the target substrate can be entered into the support means, and, optionally a means for thermal shielding of the heating means from surrounding environment is disclosed.

Foltyn, Steve R. (111 Beryl St., Los Alamos, NM 87544)

1996-01-01

281

Domain switching of fatigued ferroelectric thin films  

SciTech Connect

We investigate the domain wall speed of a ferroelectric PbZr{sub 0.48}Ti{sub 0.52}O{sub 3} (PZT) thin film using an atomic force microscope incorporated with a mercury-probe system to control the degree of electrical fatigue. The depolarization field in the PZT thin film decreases with increasing the degree of electrical fatigue. We find that the wide-range activation field previously reported in ferroelectric domains result from the change of the depolarization field caused by the electrical fatigue. Domain wall speed exhibits universal behavior to the effective electric field (defined by an applied electric field minus the depolarization field), regardless of the degree of the electrical fatigue.

Tak Lim, Yun [Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of); Yeog Son, Jong, E-mail: jyson@khu.ac.kr, E-mail: hoponpop@ulsan.ac.kr [Department of Applied Physics, College of Applied Science, Kyung Hee University, Suwon 446-701 (Korea, Republic of); Shin, Young-Han, E-mail: jyson@khu.ac.kr, E-mail: hoponpop@ulsan.ac.kr [Department of Physics and EHSRC, University of Ulsan, Ulsan 680-749 (Korea, Republic of)

2014-05-12

282

Defect formation in oxide thin films  

NASA Astrophysics Data System (ADS)

In nanosecond laser damage investigations, the specific defect density in the optical component or thin film plays the key role in triggering optical breakdown. UV irradiation can induce additional defects in optical materials before the damaging event takes place. This increased defect density can even be the main cause for UV laser damage as shown before in fused silica. Moving on to oxide thin films, this contribution will present studies on SiO2, Al2O3, and HfO2 ion beam sputtered coatings. Pure material single layers as well as composite material single layers comprised of two oxides have been investigated concerning their tendency to generate additional defects resulting from UV laser irradiation. Within this work, tests at 355 nm and 266 nm have been performed and are compared.

Jensen, Lars O.; Wagner, Frank; Mende, Mathias; Gouldieff, Céline; Blaschke, Holger; Natoli, Jean-Yves; Ristau, Detlev

2011-12-01

283

Thin film photovoltaic panel and method  

DOEpatents

A thin film photovoltaic panel includes a backcap for protecting the active components of the photovoltaic cells from adverse environmental elements. A spacing between the backcap and a top electrode layer is preferably filled with a desiccant to further reduce water vapor contamination of the environment surrounding the photovoltaic cells. The contamination of the spacing between the backcap and the cells may be further reduced by passing a selected gas through the spacing subsequent to sealing the backcap to the base of the photovoltaic panels, and once purged this spacing may be filled with an inert gas. The techniques of the present invention are preferably applied to thin film photovoltaic panels each formed from a plurality of photovoltaic cells arranged on a vitreous substrate. The stability of photovoltaic conversion efficiency remains relatively high during the life of the photovoltaic panel, and the cost of manufacturing highly efficient panels with such improved stability is significantly reduced.

Ackerman, Bruce (El Paso, TX); Albright, Scot P. (El Paso, TX); Jordan, John F. (El Paso, TX)

1991-06-11

284

Thin film strain gage development program  

NASA Technical Reports Server (NTRS)

Sputtered thin-film dynamic strain gages of 2 millimeter (0.08 in) gage length and 10 micrometer (0.0004 in) thickness were fabricated on turbojet engine blades and tested in a simulated compressor environment. Four designs were developed, two for service to 600 K (600 F) and two for service to 900 K (1200 F). The program included a detailed study of guidelines for formulating strain-gage alloys to achieve superior dynamic and static gage performance. The tests included gage factor, fatigue, temperature cycling, spin to 100,000 G, and erosion. Since the installations are 30 times thinner than conventional wire strain gage installations, and any alteration of the aerodynamic, thermal, or structural performance of the blade is correspondingly reduced, dynamic strain measurement accuracy higher than that attained with conventional gages is expected. The low profile and good adherence of the thin film elements is expected to result in improved durability over conventional gage elements in engine tests.

Grant, H. P.; Przybyszewski, J. S.; Anderson, W. L.; Claing, R. G.

1983-01-01

285

Quasicrystalline thin films: Growth, structure and interface  

NASA Astrophysics Data System (ADS)

Quasicrystals are orientation-ordered structures with classically forbidden rotation symmetries (e.g. 5-fold and 10-fold rotation axes) which are incompatible with periodic translational ordering. Quasicrystalline materials exhibit properties that are very different from conventional metallic materials. Two systems of quasicrystalline alloys have been studied in this thesis work: decagonal Al-Cu-Fe-Cr and icosahedral Al-Cu-Fe. Thin films were grown by magnetron sputtering system on various substrates and studied by Transmission Electron Microscopy, X-ray Photoelectron Spectroscopy, Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy. The growth mode at room and elevated temperatures has been investigated in-situ and ex-situ. An microstructural evolution study during the phase transformation to the quasicrystalline state has also been performed. Epitaxial quasicrystalline thin films have been successfully grown on crystalline substrates. A coincidence reciprocal lattice planes model was developed to describe the interface of quasicrystals and crystals.

Widjaja, Edy

286

Electrocaloric devices based on thin-film heat switches  

NASA Astrophysics Data System (ADS)

We describe a new approach to refrigeration, heat pumping, and electrical generation that allows one to exploit the attractive properties of thin films of electrocaloric materials. Layers of electrocaloric material coupled with thin-film heat switches can work as either refrigerators and heat pumps or electrical generators, depending on the phasing of the applied voltages and heat switching. With heat switches based on thin layers of liquid crystals, the efficiency of electrocaloric thin-film devices can be at least as high as that of current thermoelectric devices. Advanced heat switches that may use carbon nanotubes would enable thin-film refrigerators and generators to outperform conventional vapor-compression devices.

Epstein, Richard I.; Malloy, Kevin J.

2009-09-01

287

In situ growth and characterization of ultrahard thin films.  

PubMed

Results concerning the operation of a new ultrahigh vacuum (UHV) ion-beam assisted deposition system for in situ investigation of ultrahard thin films are reported. A molecular beam epitaxy (MBE) chamber attached to a surface science system (SPEAR) has been redesigned for deposition of cubic-boron nitride thin films. In situ thin film processing capability of the overall system is demonstrated in preliminary studies on deposition of boron nitride films on clean Si (001) substrates, combining thin film growth with electron microscopy and surface characterization, all in situ. PMID:9779834

Bengu, E; Collazo-Davila, C; Grozea, D; Landree, E; Widlow, I; Guruz, M; Marks, L D

1998-08-15

288

Reliability evaluation of multilevel thin film structures  

Microsoft Academic Search

IBM Microelectronics has evaluated the reliability of structures built by various processes which we developed for multilevel thin film (MLTF) applications. Two distinct processes were used for the building of conformal copper-polyimide structures on alumina ceramic: Laser ablation of the polyimide for via patterning and wiring defined by subtractive etching of Cr\\/Cu\\/Cr, and photosensitive polyimide for via patterning and wiring

Hai P. Longworth; Eric D. Perfecto; Paul V. McLaughlin

1994-01-01

289

Thin-film optical shutter. Final report  

SciTech Connect

A specific embodiment of macroconjugated macromolecules, the poly (p-phenylene)'s, has been chosen as the one most likely to meet all of the requirements of the Thin Film Optical Shutter project (TFOS). The reason for this choice is included. In order to be able to make meaningful calculations of the thermodynamic and optical properties of the poly (p-phenylene)'s a new quantum mechanical method was developed - Equilibrium Bond Length (EBL) Theory. Some results of EBL Theory are included.

Matlow, S.L.

1981-02-01

290

Packaging material for thin film lithium batteries  

DOEpatents

A thin film battery including components which are capable of reacting upon exposure to air and water vapor incorporates a packaging system which provides a barrier against the penetration of air and water vapor. The packaging system includes a protective sheath overlying and coating the battery components and can be comprised of an overlayer including metal, ceramic, a ceramic-metal combination, a parylene-metal combination, a parylene-ceramic combination or a parylene-metal-ceramic combination.

Bates, John B. (116 Baltimore Dr., Oak Ridge, TN 37830); Dudney, Nancy J. (11634 S. Monticello Rd., Knoxville, TN 37922); Weatherspoon, Kim A. (223 Wadsworth Pl., Oak Ridge, TN 37830)

1996-01-01

291

Rechargeable thin-film lithium batteries  

SciTech Connect

Rechargeable thin-film batteries consisting of lithium metal anodes, an amorphous inorganic electrolyte, and cathodes of lithium intercalation compounds have recently been developed. The batteries, which are typically less than 6-{mu}m thick, can be fabricated to any specified size, large or small, onto a variety of substrates including ceramics, semiconductors, and plastics. The cells that have been investigated include Li-TiS{sub 2}, Li-V{sub 2}O{sub 5}, and Li-Li{sub x}Mn{sub 2}O{sub 4}, with open circuit voltages at full charge of about 2.5, 3.6, and 4.2, respectively. The development of these batteries would not have been possible without the discovery of a new thin-film lithium electrolyte, lithium phosphorus oxynitride, that is stable in contact with metallic lithium at these potentials. Deposited by rf magnetron sputtering of Li{sub 3}PO{sub 4} in N{sub 2}, this material has a typical composition of Li{sub 2.9}PO{sub 3.3}N{sub 0.46} and a conductivity at 25{degrees}C of 2 {mu}S/cm. The maximum practical current density obtained from the thin-film cells is limited to about 100 {mu}A/cm{sup 2} due to a low diffusivity of Li{sup +} ions in the cathodes. In this work, the authors present a short review of their work on rechargeable thin-film lithium batteries.

Bates, J.B.; Gruzalski, G.R.; Dudney, N.J.; Luck, C.F.; Yu, Xiaohua

1993-08-01

292

Structures for dense, crack free thin films  

DOEpatents

The process described herein provides a simple and cost effective method for making crack free, high density thin ceramic film. The steps involve depositing a layer of a ceramic material on a porous or dense substrate. The deposited layer is compacted and then the resultant laminate is sintered to achieve a higher density than would have been possible without the pre-firing compaction step.

Jacobson, Craig P. (Lafayette, CA); Visco, Steven J. (Berkeley, CA); De Jonghe, Lutgard C. (Lafayette, CA)

2011-03-08

293

Overwrite in thin film disk recording systems  

Microsoft Academic Search

Overwrite in thin film rigid disk recording is studied experimentally using disks with a wide range of magnetic moment and coercivity. Standard f2\\/f1 overwrite is investigated in detail at various recording currents and different flying heights. A theoretical model is developed using simple analytical approximations that relate demagnetization-field-induced position shift (hard transition shift) to the measured overwrite. The demagnetization fields

Gang Herbert Lin; Yang Zhao; H. Neal Bertram

1993-01-01

294

Gradient Solvent Vapor Annealing of Thin Films  

Microsoft Academic Search

The development of block copolymer materials for emerging nanotechnologies requires an understanding of how surface energy\\/chemistry and annealing conditions affect thin film self-assembly. Specifically, in solvent vapor annealing (SVA), the use of solvent mixtures and the manipulation of solvent vapor concentration are promising approaches for obtaining a desired morphology or nanostructure orientation. We designed and fabricated solvent-resistant devices to produce

Julie Albert; Timothy Bogart; Ronald Lewis; Thomas Epps

2011-01-01

295

Thin film thermocouples for internal combustion engines  

Microsoft Academic Search

Procedures for fabricating thin film thermocouples on internal combustion engine hardware are examined experimentally. The techniques for growing a thermal oxide on cast iron, ferritic steel, and austenitic steel samples, representing engine hardware, with an FeCrAlY coating using an Al2O3 insulation layer are described. The adhesion, stability, and electrical performance of the aluminum oxide coating and platinum plus platinum-rhodium thermocouple

Kenneth G. Kreider

1986-01-01

296

Adhesion and Thin-Film Module Reliability  

Microsoft Academic Search

Among the infrequently measured but essential properties for thin-film (T-F) module reliability are the interlayer adhesion and cohesion within a layer. These can be cell contact layers to glass, contact layers to the semiconductor, encapsulant to cell, glass, or backsheet, etc. We use an Instron mechanical testing unit to measure peel strengths at 90deg or 180deg and, in some cases,

T. J. McMahon; G. J. Jorgensen

2006-01-01

297

Astroid plotter for thin magnetic films  

Microsoft Academic Search

The rotational astroid of uniaxial thin films may be obtained from the cross-field loopm_{x} , h_{y}graphically or electronically by assuming Slenczewski's tangent rule. The graphical construction by means of the tangent rule is demonstrated. The derivation of the transformation to obtain the astroid electronically is given, and a comparison is made with astroids obtained graphically as well as those obtained

H. Kump

1968-01-01

298

Magnetic Properties of Rhombohedral Graphene Thin Films  

NASA Astrophysics Data System (ADS)

Ever since the fabrication of single and few layers graphene, the graphene thin films have been attracting so much attention in the field not only of low-dimensional sciences but also of nano-scale technologies due to their perfect two-dimensional network. One of fascinating issues in this carbon allotrope is the intrinsic magnetism that is inherent in their topological properties. We have demonstrated that the (0001) surfaces of graphene thin film with rhombohedral-stacked arrangement exhibit ferrimagnetic spin ordering induced by flat dispersion band associated with the peculiar surface localized electron states classified as the ``edge state'' [1]. In this work, we systematically investigate how the electronic and magnetic properties of the rhombohedral-stacked graphene thin films depend on the number of graphene layers, BN substrate, and uniaxial pressure using first-principles total-energy calculations in the framework of density functional theory [2]. [4pt] [1] M. Otani, M. Koshino, Y. Takagi, and S. Okada, Phys. Rev. B 81 (2010) 161403(R). [0pt] [2] N. T. Cuong, M. Otani, and S. Okada, Surf. Sci. (2011), doi:10.1016/j.susc.2011.10.001

Cuong Nguyen, Thanh; Otani, Minoru; Okada, Susumu

2012-02-01

299

Asymmetric grain distribution in phthalocyanine thin films  

SciTech Connect

Many electronic and optical properties of organic thin films depend on the precise morphology of grains. Iron phthalocyanine thin films are grown on sapphire substrates at different temperatures to study the effect of grain growth kinematics and to experimentally quantify the grain size distribution in organic thin films. The grain size is measured with an atomic force microscope and the data is processed and analyzed with well-known image segmentation algorithms. For relevant statistics, over 3000 grains are evaluated for each sample. The data show pronounced asymmetric grain growth with increasing deposition temperature from almost spherical grains at room temperature to elongated needlelike shapes at 260 deg. C. The average size along the major axis increases from 35 to 200 nm and along the minor axis from 25 to 90 nm. The distribution is almost symmetric at low-deposition temperatures, but becomes lognormal at higher temperatures. Strikingly, the major axis and minor axis of the elliptically shaped grains have different distributions at all temperatures due to the planar asymmetry of the molecule.

Gentry, K. Paul; Gredig, Thomas; Schuller, Ivan K. [Department of Physics and Astronomy, California State University-Long Beach, 1250 Bellflower Boulevard, Long Beach, California 90840 (United States); Department of Physics and Astronomy, University of California-San Diego, 9500 Gilman Drive, La Jolla, California 92093 (United States)

2009-11-01

300

Comparison of the pinning energy in Fe(Se1-xTex) compound between single crystals and thin films  

NASA Astrophysics Data System (ADS)

Among the families of iron-based superconductors, we investigate flux pinning mechanisms in the Fe(Se1-xTex) compound. We perform magneto-resistance and current-voltage measurements on single-crystals, as well as on several epitaxial thin films grown on different substrates (CaF2, LaAlO3). The activation energy is derived as a function of magnetic field, U(H). The influence of magnetic field orientation on the pinning energy activation mechanism is also studied, leading to the anisotropy analysis which reveals low anisotropy in thin films grown on CaF2 substrate with respect to single crystals and films grown on LaAlO3. Concerning the dominant pinning regime, the exponents of the power law dependence U0(H) ~ H-? have been evaluated, confirm that weak pinning is a general characteristic of this compound. The single exponent feature, generally noticed on thin films grown on SrTiO3 substrate and associated to a strong single vortex regime, has been observed in thin films grown on LaAlO3, only in the parallel configuration. At the end, this overall comparison can be useful to develop a technological material able to compete with high temperature superconductors.

Leo, A.; Guarino, A.; Grimaldi, G.; Nigro, A.; Pace, S.; Bellingeri, E.; Kawale, S.; Ferdeghini, C.; Giannini, E.

2014-05-01

301

Tensor permittivity measurements of thin films at millimeter wavelengths  

Microsoft Academic Search

Although thin dielectric films are finding more applications in microwave and millimeter-wave circuits, measurement of their dielectric properties presents some unique problems, especially if the films are anisotropic and properly characterized by a permitivity tensor. We have developed a folded open-cavity resonator to aid in the determination of the three tensor permittivity matrix elements of anisotropic thin films with thicknesses

Jing-Fu Zhao; Karl D. Stephan; Sai-Chu Wong; Roger S. Porter

1988-01-01

302

The thin dielectric film capacitive displacement transducer to nanometer  

Microsoft Academic Search

The paper deals with the new capacitive transducer for small displacements (from a few micrometers to a few millimeters), denoted the Thin Dielectric Film Capacitive Displacement Transducer (TFCDT). This principle is based on the properties of a very thin dielectric film between the faced electrodes. The film may be applied by a dielectric, such as alumina. The transducers are designed

Franco Castelli

2001-01-01

303

Fracture patterns in thin films and multilayers Alex A. Volinsky  

E-print Network

a network of through-thickness cracks forms in the film. In the case of compressive stress thin film. INTRODUCTION Thin films can support high levels of residual stress (up to several GPa), which are typically higher in compression compared to tension. Regardless of the residual stress sign, it causes substrate

Volinsky, Alex A.

304

Chemical bath method for ZnS thin films preparation  

Microsoft Academic Search

We report a chemical bath method to prepare ZnS thin films on glass substrates for solar applications. The proposed method is based on the experience to deposit CdS thin films by chemical bath but replacing some chemical reagents. The bath is composed of zinc chloride, potassium hydroxide, ammonium nitrate, and thiourea. During films deposition, the chemical bath is agitated with

Andrés Iván Oliva; I. Gonza?lez-Chan; V. Rejo?n; J. Rojas; R. Patiño; D. Aguilar

2010-01-01

305

Polymer-Metal Nanocomposites via Polymer Thin Film  

E-print Network

Polymer-Metal Nanocomposites via Polymer Thin Film T. P. Radhakrishnan School of Chemistry, University of Hyderabad Polymer-metal nanocomposite thin films are versatile materials that not only characteristics of the components, but also manifest mutualistic effects. Soft c film is a facile in situ of metal

Shyamasundar, R.K.

306

SAND2003-8146C Symposium on Thin Films  

E-print Network

SAND2003-8146C Symposium on Thin Films ICM-9 9th International Conference on the Mechanical GOLD FILMS N. R. Moody, D. P. Adams*, M. J. Cordill**, D. F. Bahr**, A. A. Volinsky*** Sandia National FRACTURE OF THIN GOLD FILMS N. R. Moody, D. P. Adams*, M. J. Cordill**, D. F. Bahr**, A. A. Volinsky

Volinsky, Alex A.

307

Stoichiometry control of magnetron sputtered Bi2Sr2Ca1xYxCu2Oy (0 6 x 6 0.5) thin film, composition  

E-print Network

Stoichiometry control of magnetron sputtered Bi2Sr2Ca1Ã?xYxCu2Oy (0 6 x 6 0.5) thin film Received 15 April 2005; accepted 3 June 2005 Available online 15 July 2005 Abstract A magnetron sputtering superconductors (high-Tc and insulating parent compound); Composition spread libraries; Magnetron sputtering

Hewitt, Kevin

308

Gravitationally-Driven Drainage of Thin Films  

NASA Astrophysics Data System (ADS)

A two-dimensional mathematical model is constructed to study the evolution of a vertically-oriented thin liquid film draining under gravity when there is an insoluble surfactant with finite surface viscosity on its free surface. Lubrication theory for this free film results in three coupled nonlinear partial differential equations (PDEs) describing the free surface shape, the surface velocity and the surfactant transport at leading order. The draining film terminates on a static meniscus. We will show that in the limit of large surface viscosity, the evolution of the free surface is that obtained for the tangentially-immobile case. For mobile films with small surface viscosity, transistion from a mobile to an immobile film is observed for large Marangoni number. It is verified that increasing surface viscosity and the Marangoni effect retards drainage thereby enhancing film stability. The theoretical results are compared with experiment performed by Snow and co-workers at Dow Corning; the purpose of both is to act as a model problem to evaluate the effectiveness of surfactants for potential use in foam-fabrication processes.

Naire, Shailesh; Braun, Richard. J.; Snow, Steven. A.

1999-11-01

309

Electronic evidence of an insulator-superconductor crossover in single-layer FeSe/SrTiO3 films.  

PubMed

In high-temperature cuprate superconductors, it is now generally agreed that superconductivity is realized by doping an antiferromagnetic Mott (charge transfer) insulator. The doping-induced insulator-to-superconductor transition has been widely observed in cuprates, which provides important information for understanding the superconductivity mechanism. In the iron-based superconductors, however, the parent compound is mostly antiferromagnetic bad metal, raising a debate on whether an appropriate starting point should go with an itinerant picture or a localized picture. No evidence of doping-induced insulator-superconductor transition (or crossover) has been reported in the iron-based compounds so far. Here, we report an electronic evidence of an insulator-superconductor crossover observed in the single-layer FeSe film grown on a SrTiO3 substrate. By taking angle-resolved photoemission measurements on the electronic structure and energy gap, we have identified a clear evolution of an insulator to a superconductor with increasing carrier concentration. In particular, the insulator-superconductor crossover in FeSe/SrTiO3 film exhibits similar behaviors to that observed in the cuprate superconductors. Our results suggest that the observed insulator-superconductor crossover may be associated with the two-dimensionality that enhances electron localization or correlation. The reduced dimensionality and the interfacial effect provide a new pathway in searching for new phenomena and novel superconductors with a high transition temperature. PMID:25502774

He, Junfeng; Liu, Xu; Zhang, Wenhao; Zhao, Lin; Liu, Defa; He, Shaolong; Mou, Daixiang; Li, Fangsen; Tang, Chenjia; Li, Zhi; Wang, Lili; Peng, Yingying; Liu, Yan; Chen, Chaoyu; Yu, Li; Liu, Guodong; Dong, Xiaoli; Zhang, Jun; Chen, Chuangtian; Xu, Zuyan; Chen, Xi; Ma, Xucun; Xue, Qikun; Zhou, X J

2014-12-30

310

Thin film cadmium telluride photovoltaic cells  

SciTech Connect

This report describes research to develop to vacuum-based growth techniques for CdTe thin-film solar cells: (1) laser-driven physical vapor deposition (LDPVD) and (2) radio-frequency (rf) sputtering. The LDPVD process was successfully used to deposit thin films of CdS, CdTe, and CdCl{sub 2}, as well as related alloys and doped semiconductor materials. The laser-driven deposition process readily permits the use of several target materials in the same vacuum chamber and, thus, complete solar cell structures were fabricated on SnO{sub 2}-coated glass using LDPVD. The rf sputtering process for film growth became operational, and progress was made in implementing it. Time was also devoted to enhancing or implementing a variety of film characterization systems and device testing facilities. A new system for transient spectroscopy on the ablation plume provided important new information on the physical mechanisms of LDPVD. The measurements show that, e.g., Cd is predominantly in the neutral atomic state in the plume but with a fraction that is highly excited internally ({ge} 6 eV), and that the typical neutral Cd translational kinetic energies perpendicular to the target are 20 eV and greater. 19 refs.

Compaan, A.; Bohn, R. (Toledo Univ., OH (United States))

1992-04-01

311

Stabilization mechanism of electrodeposited silicon thin films.  

PubMed

Amorphous composite silicon thin films electrodeposited in tetrahydrofuran, containing up to 80 at% of Si and exhibiting an homogeneous dispersions of O, C and Cl in the amorphous Si matrix, have been successfully stabilized against oxidation using a post-annealing step in inert atmosphere. In order to understand the impact of the annealing step on their stabilization against oxidation, their composition and structure have been investigated upon heat treatments. It has been shown that the presence of impurities such as O, C and Cl does not have any impact on the stabilization process, which is rather linked to the presence of hydrogen in the Si composites. This conclusion has been drawn after a detailed analysis of the bonding structure of films annealed at different temperatures and dwell times by the mean of Raman spectroscopy. It has been shown that annealing the as-deposited films at 350 °C for a couple of hours or at higher temperatures induced a hydrogen evolution, characterized by the breaking of Si-H bonds and the formation of Si-Si bonds, which stabilized the silicon network. The understanding and the reproducibility of this stabilization process of silicon thin film electrodeposited in organic solvent paves the way for their use for many applications. PMID:25212513

Vichery, C; Le Nader, V; Frantz, C; Zhang, Y; Michler, J; Philippe, L

2014-10-28

312

Leakage currents in thin ferroelectric films  

NASA Astrophysics Data System (ADS)

The basic mechanisms of leakage current components of thin lead zirconate titanate (PZT) ferroelectric films grown by the sol-gel method have been studied. Characteristic regions of current-voltage characteristics with different charge transport mechanisms have been determined. It has been shown that there is an intermediate region which separates such regions. In one of them, the leakage current depends on properties of the contact of electrodes with PZT film at low voltages; in the other, the leakage current is controlled by intrinsic properties of the PZT film bulk, and the basic mechanism of charge transport is Poole-Frenkel emission. In the intermediate region, a stepwise change in the current has been observed, which is caused by relaxing breakdown of the Schottky barrier. Time dependences of the leakage currents have been determined. It has been shown that the leakage current decreases with increasing delay time before the Schottky barrier breakdown, and the dependence becomes opposite in character after the breakdown.

Podgornyi, Yu. V.; Vorotilov, K. A.; Sigov, A. S.

2012-05-01

313

Nanocrystalline silicon based thin film solar cells  

NASA Astrophysics Data System (ADS)

Amorphous silicon solar cells and panels on glass and flexible substrate are commercially available. Since last few years nanocrystalline silicon thin film has attracted remarkable attention due to its stability under light and ability to absorb longer wavelength portion of solar spectrum. For amorphous silicon/ nanocrystalline silicon double junction solar cell 14.7% efficiency has been achieved in small area and 13.5% for large area modules internationally. The device quality nanocrystalline silicon films have been fabricated by RF and VHF PECVD methods at IACS. Detailed characterizations of the materials have been done. Nanocrystalline films with low defect density and high stability have been developed and used as absorber layer of solar cells.

Ray, Swati

2012-06-01

314

Metal-doped magnetite thin films.  

PubMed

This paper investigates magnetite (Fe3O4) thin film containing a small amount of a metal element. The films are prepared by rf sputtering with a composite target of ceramic iron oxide with metal chips. Low-temperature magnetization of magnetite containing 5.3%Ge reveals that the film contains some magnetically weak coupling grains. The metal element Mg reduces both hematite (alpha-Fe2O3) and magnetite, resulting in single-phase wüstite (Fe1-xO). In contrast, adding Ge selectively reduces hematite, while magnetite remains unreactive. According to the free energy of reaction, the element Ge is able to reduce hematite only, whereas the element Mg is capable of reducing both hematite and magnetite. This property is in good agreement with the experiment results. PMID:22905582

Abe, Seishi; Ping, De Hai; Nakamura, Shintaro; Ohnuma, Masato; Ohnuma, Shigehiro

2012-06-01

315

Negative differential conductivity in thin ferroelectric films  

NASA Astrophysics Data System (ADS)

A phenomenon of negative differential conductivity in ferroelectric thin films is discussed. We proposed that the reason is polarization recovery current arising at current-voltage I(V) measurements as a result of polarization relaxation after pre-polarization of ferroelectric film. Simulation of this current by Weibull distribution provides a good correlation with the experimental data. The obtained values of the recovered polarization Prec and the field strength Erec at which the recovery polarization current reaches maximum do not depend on the voltage sweep rate and are well correlated with the values of polarization relaxation Prel and coercive field strength Ec obtained from dielectric hysteresis loop. It is shown that the current density due to polarization recovery Jrec may exceed by about an order the ohmic current density J? in ferroelectric film at Ec.

Podgorny, Yury; Vorotilov, Konstantin; Sigov, Alexander

2014-11-01

316

Oriented thin films of perylenetetracarboxylic diimide on frictiontransferred polymer films  

Microsoft Academic Search

Perylenetetracarboxylic diimide (PTCDI) is a promising material for application in organic electronics. In this study we report on the preparation of oriented thin films of PTCDI on the surface of oriented polymer substrates, which were prepared by friction transfer method. Two polymers, poly(tetrafluoroethylene) (PTFE) and poly(p-phenylene) (PPP) were used as the orienting substrate for PTCDI for comparison studies. Characterization by

Nobutaka Tanigaki; Claire Heck; Toshiko Mizokuro

2011-01-01

317

Magnetoimpedance spectroscopy of epitaxial multiferroic thin films  

NASA Astrophysics Data System (ADS)

The detection of true magnetocapacitance (MC) as a manifestation of magnetoelectric coupling (MEC) in multiferroic materials is a nontrivial task, because pure magnetoresistance (MR) of an extrinsic Maxwell-Wagner-type dielectric relaxation can lead to changes in capacitance [G. Catalan, Appl. Phys. Lett.APPLAB0003-695110.1063/1.2177543 88, 102902 (2006)]. In order to clarify such difficulties involved with dielectric spectroscopy on multiferroic materials, we have simulated the dielectric permittivity ?' of two dielectric relaxations in terms of a series of one intrinsic film-type and one extrinsic Maxwell-Wagner-type relaxation. Such a series of two relaxations was represented in the frequency- (f-) and temperature- (T-) dependent notations ?' vs f and ?' vs T by a circuit model consisting in a series of two ideal resistor-capacitor (RC) elements. Such simulations enabled rationalizing experimental f-, T-, and magnetic field- (H-) dependent dielectric spectroscopy data from multiferroic epitaxial thin films of BiMnO3 (BMO) and BiFeO3 (BFO) grown on Nb-doped SrTiO3. Concomitantly, the deconvolution of intrinsic film and extrinsic Maxwell-Wagner relaxations in BMO and BFO films was achieved by fitting f-dependent dielectric data to an adequate equivalent circuit model. Analysis of the H-dependent data in the form of determining the H-dependent values of the equivalent circuit resistors and capacitors then yielded the deconvoluted MC and MR values for the separated intrinsic dielectric relaxations in BMO and BFO thin films. Substantial intrinsic MR effects up to 65% in BMO films below the magnetic transition (TC?100 K) and perceptible intrinsic MEC up to -1.5% near TC were identified unambiguously.

Schmidt, Rainer; Ventura, Jofre; Langenberg, Eric; Nemes, Norbert M.; Munuera, Carmen; Varela, Manuel; Garcia-Hernandez, Mar; Leon, Carlos; Santamaria, Jacobo

2012-07-01

318

Thin Film Evolution Over a Thin Porous Layer: Modeling a Tear Film on a Contact Lens  

NASA Astrophysics Data System (ADS)

We examine a mathematical model that describes the behavior of the pre-contact lens tear film of a human eye. Our work examines the effect of contact lens thickness and lens permeability and slip on the film dynamics. A mathematical model for the evolution of the tear film is derived using a lubrication approximation applied to the hydrodynamic equations of motion in the fluid film and the porous layer. The model is a nonlinear fourth order partial differential equation subject to boundary conditions and an initial condition for post-blink film evolution. We find that increasing the lens thickness, permeability and slip all contribute to an increase in the film thinning rate although for parameter values typical for contact lens wear these modifications are minor. The presence of the contact lens can, however, fundamentally change the nature of the rupture dynamics as the inclusion of the porous lens leads to rupture in finite time rather than infinite time.

Anderson, Daniel; Nong, Kumnit

2010-11-01

319

Semiconductor thin-film optical constant determination and thin-film thickness measurement equipment correlation  

NASA Astrophysics Data System (ADS)

There are several methods for correlating thin film thickness measurement equipment. The most commonly used method is to program in an offset that gets systematically added to or subtracted from the thickness calculation. Measurement errors can occur using this 'fudge factor' method because the relationship between the reference thicknesses and the measured thicknesses is not, in general, a fixed constant or simple function. A better method for correlating thin film thickness measurement equipment is to tune the instruments to the process by refining the internal optical constants.

Kaiser, Anne M.

1991-07-01

320

Study of Microwave Dielectric Properties of Perovskite Thin Films by Near-Field Microscopy  

Microsoft Academic Search

Perovskite thin film materials possess good dielectric properties, which vary with applied voltage, and have thus been thoroughly investigated for applications as thin film tunable microwave devices. However, the tunability of the thin film materials derived from the frequency response of the thin film devices suffers from ambiguity in extracting the true dielectric response of the thin film materials in

Yi-Chun Chen; Yun-Shuo Hsieh; Hsiu-Fung Cheng; I-Nan Lin

2004-01-01

321

Chemical bath deposition of crystalline ZnS thin films  

Microsoft Academic Search

Crystalline zinc sulfide (ZnS) thin films were prepared by chemical bath deposition (CBD) using the mixed aqueous solutions of zinc acetate, thiourea and tri-sodium citrate, where tri-sodium citrate was used as the complexing agent. The thin films were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM) and optical absorption. The as-deposited thin films were surface homogeneous with pure wurtzite

Jie Cheng; Dong Bo Fan; Hao Wang; Bing Wei Liu; Yong Cai Zhang; Hui Yan

2003-01-01

322

Cadmium Sulfide Thin Films Grown By Chemical Bath Deposition Method  

Microsoft Academic Search

CdS thin films were deposited by the chemical bath deposition (CBD) from a bath containing CdSO4, thiourea and ammonia. The effect of annealing in air on the optical properties of CdS thin films was investigated. The quality of CBD CdS thin films was analyzed at different condition of temperature, concentration of reactants and deposition time. The optical band gap of

S. Erat; H. Metin

2007-01-01

323

Investigation of Paraelectric Plt Thin Films Using Reactive Magnetron Sputtering  

Microsoft Academic Search

The study of methods to prepare paraelectric perovskite PLT (Pb_{rm 1-X} La_{rm X}Ti _{rm 1-X\\/4}O_3 ; x = 0.28) thin films has been important because thin films of this high dielectric strength material are required to make high density capacitors for dynamic random access memory. In this research, paraelectric PLT thin films were prepared on multi-layer (Pt\\/Ti\\/SiO_2 \\/Si) and MgO

Hyun Hoo Kim

1994-01-01

324

Thermoluminescence of aluminum oxide thin films subject to ultraviolet irradiation  

Microsoft Academic Search

The thermoluminescence (TL) properties of amorphous aluminum oxide thin films subjected to ultraviolet (UV) irradiation are reported. Aluminum oxide thin films were prepared by laser ablation from an ?-Al2O3 target using Nd:YAG laser with emission at the fundamental line. Compositional, structural and morphological properties of the obtained thin films as a function of the growth conditions have been studied. Experimental

L. Escobar-Alarcón; E. Villagrán; E. Camps; S. Romero; J. E. Villarreal-Barajas; P. R. González

2003-01-01

325

Physical properties of polyazomethine thin films doped with iodine  

Microsoft Academic Search

Purpose: The aim of this paper is to show influence of doping 1,4-phenylene-methylenenitrilo-1,4- phenylenenitrilomethylene (PPI) with iodine and to propose doping mechanism and its impact on electronic structure of doped PPI thin films. Design\\/methodology\\/approach: Influence of iodine doping on electronic structure of polyazomethine thin films was investigated. Optical absorption spectra, XRD spectra and AFM images of doped PPI thin films

B. Hajduk; J. Weszka; J. Jurusik; M. Curie-Sklodowska

326

Commercial status of thin-film photovoltaic devices and materials.  

PubMed

We present a review of commercial thin-film photovoltaic (PV) technologies and products. After a brief introduction of recent dynamics in the on-grid PV market, we provide an overview of commercial thin-film silicon, cadmium telluride, copper indium gallium diselenide, and organic PV modules - including representative efficiencies, deposition processes, module form factors, and nominal production capacities available for production today. Finally, we discuss the technical, production, and market targets of thin-film PV module developers. PMID:21165078

Schmidtke, Johanna

2010-09-13

327

Silicon films with gallium-rich nanoinclusions: from superconductor to insulator  

NASA Astrophysics Data System (ADS)

Si films sputter deposited on thermally oxidized Si are enriched with Ga by ion implantation through a SiO2 capping layer. The morphology and the electrical transport properties of these films are investigated after rapid thermal annealing. Amorphous, Ga-rich nanoinclusions are embedded in a nanocrystalline Si matrix. The metallic nanoinclusions become superconducting below 7 K. They form a random network of junctions to heavily doped Si crystallites. Small modifications of the junction properties, e.g. by annealing or current pulses, can dramatically change the electronic transport in the film. Ga-rich Si films show a wealth of low-temperature transport phenomena, which have been known until now only from granular metals or high-temperature superconductors: superconductor-insulator transition, quasi-reentrant superconductivity and current-controlled sheet resistance. The possibility to prepare and modify Ga-rich Si films with microelectronics-compatible technology makes them interesting for both fundamental research on transport phenomena in nanostructured, disordered superconductors as well as for the integration of superconducting circuits into Si devices.

Heera, V.; Fiedler, J.; Hübner, R.; Schmidt, B.; Voelskow, M.; Skorupa, W.; Skrotzki, R.; Herrmannsdörfer, T.; Wosnitza, J.; Helm, M.

2013-08-01

328

"Perfect" Electrochemical Molecular Sieving by Thin and Ultrathin Metallopolymeric Films  

E-print Network

molecular structure with the observed electrochemical reactivity. Molecular sieving behavior is discussed"Perfect" Electrochemical Molecular Sieving by Thin and Ultrathin Metallopolymeric Films Suzanne Be by formation of nonelectroactive films, which are electronically insulating at least over the electrochemical

329

Chemical vapor deposition of organosilicon and sacrificial polymer thin films  

E-print Network

Chemical vapor deposition (CVD) produced films for a wide array of applications from a variety of organosilicon and organic precursors. The structure and properties of thin films were controlled by varying processing ...

Casserly, Thomas Bryan

2005-01-01

330

Fluorination of amorphous thin-film materials with xenon fluoride  

DOEpatents

A method is disclosed for producing fluorine-containing amorphous semiconductor material, preferably comprising amorphous silicon. The method includes depositing amorphous thin-film material onto a substrate while introducing xenon fluoride during the film deposition process.

Weil, Raoul B. (Haifa, IL)

1988-01-01

331

Fluorination of amorphous thin-film materials with xenon fluoride  

DOEpatents

A method is disclosed for producing fluorine-containing amorphous semiconductor material, preferably comprising amorphous silicon. The method includes depositing amorphous thin-film material onto a substrate while introducing xenon fluoride during the film deposition process.

Weil, R.B.

1987-05-01

332

Progress on thin-film sensors for space propulsion technology  

NASA Astrophysics Data System (ADS)

The objective is to develop thin-film thermocouples for Space Shuttle Main Engine (SSME) components. Thin-film thermocouples have been developed for aircraft gas turbine engines and are in use for temperature measurement on turbine blades to 1800 F. The technology established for aircraft gas turbine engines will be adapted to the materials and environment encountered in the SSME. Specific goals are to expand the existing in-house thin-film sensor technology and to test the survivability and durability of thin-film sensors in the SSME environment.

Kim, Walter S.

333

Uncooled thin film pyroelectric IR detector with aerogel thermal isolation  

DOEpatents

A monolithic infrared detector structure which allows integration of pyroelectric thin films atop low thermal conductivity aerogel thin films. The structure comprises, from bottom to top, a substrate, an aerogel insulating layer, a lower electrode, a pyroelectric layer, and an upper electrode layer capped by a blacking layer. The aerogel can offer thermal conductivity less than that of air, while providing a much stronger monolithic alternative to cantilevered or suspended air-gap structures for pyroelectric thin film pixel arrays. Pb(Zr.sub.0.4 Ti.sub.0.6)O.sub.3 thin films deposited on these structures displayed viable pyroelectric properties, while processed at 550.degree. C.

Ruffner, Judith A. (Albuquerque, NM); Bullington, Jeff A. (Albuquerque, NM); Clem, Paul G. (Albuquerque, NM); Warren, William L. (Albuquerque, NM); Brinker, C. Jeffrey (Albuquerque, NM); Tuttle, Bruce A. (Albuquerque, NM); Schwartz, Robert W. (Seneca, SC)

1999-01-01

334

Progress on thin-film sensors for space propulsion technology  

NASA Technical Reports Server (NTRS)

The objective is to develop thin-film thermocouples for Space Shuttle Main Engine (SSME) components. Thin-film thermocouples have been developed for aircraft gas turbine engines and are in use for temperature measurement on turbine blades to 1800 F. The technology established for aircraft gas turbine engines will be adapted to the materials and environment encountered in the SSME. Specific goals are to expand the existing in-house thin-film sensor technology and to test the survivability and durability of thin-film sensors in the SSME environment.

Kim, Walter S.

1987-01-01

335

Polycrystalline Thin-Film Photovoltaic Technologies: Progress and Technical Issues  

Microsoft Academic Search

Polycrystalline thin-film materials based on copper indium diselenide (CuInSe2, CIS) and cadmium telluride (CdTe) are promising thin-film solar cells for various power and specialty applications. Impressive results have been obtained in the past few years for both thin-film copper indium gallium diselenide (CIGS) solar cells and thin-film CdTe solar cells. NCPV\\/NREL scientists have achieved world-record, total-area efficiencies of 19.3% for

Harin S. Ullal

2004-01-01

336

Applications of thin-film photovoltaics for space  

NASA Technical Reports Server (NTRS)

The authors discuss the potential applications of thin-film polycrystalline and amorphous cells for space. There have been great advances in thin-film solar cells for terrestrial applications. Transfer of this technology to space applications could result in ultra low-weight solar arrays with potentially large gains in specific power. Recent advances in thin-film solar cells are reviewed, including polycrystalline copper indium selenide and related I-III-VI2 compounds, polycrystalline cadmium telluride and related II-VI compounds, and amorphous silicon arrays. The possibility of using thin-film multi-bandgap cascade solar cells is discussed.

Landis, Geoffrey A.; Hepp, Aloysius F.

1991-01-01

337

Thin-Film Photovoltaics: Status and Applications to Space Power  

NASA Technical Reports Server (NTRS)

The potential applications of thin film polycrystalline and amorphous cells for space are discussed. There have been great advances in thin film solar cells for terrestrial applications; transfer of this technology to space applications could result in ultra low weight solar arrays with potentially large gains in specific power. Recent advances in thin film solar cells are reviewed, including polycrystalline copper iridium selenide and related I-III-VI2 compounds, polycrystalline cadmium telluride and related II-VI compounds, and amorphous silicon alloys. The possibility of thin film multi bandgap cascade solar cells is discussed.

Landis, Geoffrey A.; Hepp, Aloysius F.

1991-01-01

338

Strain tuning of ferroelectric thin films.  

SciTech Connect

Predictions and measurements of the effect of biaxial strain on the properties of epitaxial ferroelectric thin films and superlattices are reviewed. Results for single-layer ferroelectric films of biaxially strained SrTiO{sub 3}, BaTiO{sub 3}, and PbTiO{sub 3} as well as PbTiO{sub 3}/SrTiO{sub 3} and BaTiO{sub 3}/SrTiO{sub 3} superlattices are described. Theoretical approaches, including first principles, thermodynamic analysis, and phase-field models, are applied to these biaxially strained materials, the assumptions and limitations of each technique are explained, and the predictions are compared. Measurements of the effect of biaxial strain on the paraelectric-to-ferroelectric transition temperature (T{sub c}) are shown, demonstrating the ability of percent-level strains to shift T{sub c} by hundreds of degrees in agreement with the predictions that predated such experiments. Along the way, important experimental techniques for characterizing the properties of strained ferroelectric thin films and superlattices, as well as appropriate substrates on which to grow them, are mentioned.

Schlom, D. G.; Chen, L.-Q.; Eom, C.-B.; Rabe, K. M.; Streiffer, S. K.; Triscone, J.-M.; Penn State Univ.; Univ. of Wisconsin at Madison; Rutgers Univ.; Univ. of Geneva

2007-01-01

339

Onset of plasticity in thin polystyrene films.  

PubMed

Polymer glasses have numerous advantageous mechanical properties in comparison to other materials. One of the most useful is the high degree of toughness that can be achieved due to significant yield occurring in the material. Remarkably, the onset of plasticity in polymeric materials is very poorly quantified, despite its importance as the ultimate limit of purely elastic behavior. Here, we report the results of a novel experiment which is extremely sensitive to the onset of yield and discuss its impact on measurement and elastic theory. In particular, we use an elastic instability to locally bend and impart a local tensile stress in a thin, glassy polystyrene film, and directly measure the resulting residual stress caused by the bending. We show that plastic failure is initiated at extremely low strains, of the order 10(-3) for polystyrene. Not only is this critical strain found to be small in comparison to bulk measurement, we show that it is influenced by thin film confinement--leading to an increase in the critical strain for plastic failure as film thickness approaches zero. PMID:25166374

Gurmessa, Bekele J; Croll, Andrew B

2013-02-15

340

Chemical analysis of the plasma-polymerized diphenyl thin films  

Microsoft Academic Search

Plasma-polymerized diphenyl (PPDP) thin films were prepared by glow discharge technique. The PPDP films were characterized by scanning electron microscopy (SEM), elemental analysis, infrared (IR) spectroscopy, Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). The surface morphology of the PPDP film is observed to be uniform and pinhole-free. The IR analysis reveals that the structure of PPDP thin film

F.-U.-Z Chowdhury; A. B. M. O Islam; A. H Bhuiyan

2000-01-01

341

Influence of ion beam mixing on the growth of high temperature oxide superconducting thin film  

SciTech Connect

The superconducting properties of high temperature superconductor thin films are dependent on the quality of the substrate used to grow these films. In order to maximize the lattice matching between the superconducting film and the substrate, we have used a YBa{sub 2}Cu{sub 3}O{sub 7} thin film deposited on {l angle}100{r angle} SrTiO{sub 3} as a template. The first film was prepared by coevaporation of Y, BaF{sub 2} and Cu on {l angle}100{r angle} SrTiO{sub 3}, followed by an anneal in wet'' oxygen at 850{degree}C. This film showed a sharp transition at about 90 K. A thicker layer of about 5000 A was then deposited on top of this first 2000 {angstrom} film, using the same procedure. After the post anneal at 850{degree}C, the transition took place at 80 K and no epitaxy of the second film was observed. Ion beam mixing at 400{degree}C, using 400 keV O ions was done at the interface of the two films (the second one being not annealed). After the post anneal, the film displayed an improved Tc at 90K. Moreover, epitaxy was shown to take place from the interface SrTiO{sub 3}-123 film towards the surface and was dependent of the dose. These results will be discussed from the data obtained from Rutherford backscattering spectroscopy (RBS) combined with channeling experiments, x-ray diffraction (XRD) and scanning electron microscopy (SEM) observations. 8 refs., 2 figs., 2 tabs.

Bordes, N.; Rollett, A.D.; Cohen, M.R.; Nastasi, M.

1989-01-01

342

Polycrystalline-thin-film thermophotovoltaic cells  

NASA Astrophysics Data System (ADS)

Thermophotovoltaic (TPV) cells convert thermal energy to electricity. Modularity, portability, silent operation, absence of moving parts, reduced air pollution, rapid start-up, high power densities, potentially high conversion efficiencies, choice of a wide range of heat sources employing fossil fuels, biomass, and even solar radiation are key advantages of TPV cells in comparison with fuel cells, thermionic and thermoelectric convertors, and heat engines. The potential applications of TPV systems include: remote electricity supplies, transportation, co-generation, electric-grid independent appliances, and space, aerospace, and military power applications. The range of bandgaps for achieving high conversion efficiencies using low temperature (1000-2000 K) black-body or selective radiators is in the 0.5-0.75 eV range. Present high efficiency convertors are based on single crystalline materials such as In1-xGaxAs, GaSb, and Ga1-xInxSb. Several polycrystalline thin films such as Hg1-xCdxTe, Sn1-xCd2xTe2, and Pb1-xCdxTe, etc., have great potential for economic large-scale applications. A small fraction of the high concentration of charge carriers generated at high fluences effectively saturates the large density of defects in polycrystalline thin films. Photovoltaic conversion efficiencies of polycrystalline thin films and PV solar cells are comparable to single crystalline Si solar cells, e.g., 17.1% for CuIn1-xGaxSe2 and 15.8% for CdTe. The best recombination-state density Nt is in the range of 10-15-10-16 cm-3 acceptable for TPV applications. Higher efficiencies may be achieved because of the higher fluences, possibility of bandgap tailoring, and use of selective emitters such as rare earth oxides (erbia, holmia, yttria) and rare earth-yttrium aluminium garnets. As compared to higher bandgap semiconductors such as CdTe, it is easier to dope the lower bandgap semiconductors. TPV cell development can benefit from the more mature PV solar cell and opto-electronic (infrared detectors, lasers, and optical communications) technologies. Low bandgaps and larger fluences employed in TPV cells result in very high current densities which make it difficult to collect the current effectively. Techniques for laser and mechanical scribing, integral interconnection, and multi-junction tandem structures which have been fairly well developed for thin-film PV solar cells could be further refined for enhancing the voltages from TPV modules. Thin-film TPV cells may be deposited on metals or back-surface reflectors. Spectral control elements such as indium-tin oxide or tin oxide may be deposited directly on the TPV convertor. It would be possible to reduce the cost of TPV technologies based on single-crystal materials being developed at present to the range of US 2-5 per watt so as to be competitive in small to medium size commercial applications. However, a further cost reduction to the range of US ¢ 35- 1 per watt to reach the more competitive large-scale residential, consumer, and hybrid-electric car markets would be possible only with the polycrystalline-thin film TPV cells.

Dhere, Neelkanth G.

1996-02-01

343

Electronic Properties of Cesium Oxide Thin Films  

NASA Astrophysics Data System (ADS)

In the recent years research on surface production H^- ion has been strongly motivated by the need of intense neutral H beams in controlled-fusion and Strategic Defense Initiative applications. Low work function surfaces are of great importance for high-efficiency H^- productions. Cesium-oxide thin films are one of the most important low-work-function materials. The electronic properties of cesium-oxygen-composite thin films deposited on metal (molybdenum) and semiconductor (silicon) substrates are investigated. The surface is characterized using Auger electron spectroscopy (AES), ultraviolet photoelectron spectroscopy (UPS), work function probe and thermal desorption spectroscopy (TDS). Experiments are performed in an ultra -high vacuum (UHV) surface analysis system. Cs/O thin film deposition on Si(100) is accomplished by depositing a monolayer of cesium (using a 20 eV low energy cesium ion gun) and followed by exposure to O _2 gas, which results in a minimum work function of 0.9 eV. Various cesium oxide species are formed during the oxidation of cesiated Si(100), and the minimum work function is due to the formation of a special Cs-O-Si(100) surface structure that is related to the reconstructed Si(100) and Cs_2O_2 . We also studied a 0.5 ?m coating on a molybdenum substrate produced by thermal decomposition of Cs_2CO_3 at 920 K. Work function of 0.9 eV is achieved with a sample temperature of 470 K, due to a significant increase of the bulk conductivity. This low work function is maintained for many hours under UHV condition and the sample is completely stable in an atomic hydrogen environment.

Huang, Handing

1992-01-01

344

Rechargeable thin-film electrochemical generator  

DOEpatents

An improved electrochemical generator is disclosed. The electrochemical generator includes a thin-film electrochemical cell which is maintained in a state of compression through use of an internal or an external pressure apparatus. A thermal conductor, which is connected to at least one of the positive or negative contacts of the cell, conducts current into and out of the cell and also conducts thermal energy between the cell and thermally conductive, electrically resistive material disposed on a vessel wall adjacent the conductor. The thermally conductive, electrically resistive material may include an anodized coating or a thin sheet of a plastic, mineral-based material or conductive polymer material. The thermal conductor is fabricated to include a resilient portion which expands and contracts to maintain mechanical contact between the cell and the thermally conductive material in the presence of relative movement between the cell and the wall structure. The electrochemical generator may be disposed in a hermetically sealed housing.

Rouillard, Roger (Beloeil, CA); Domroese, Michael K. (South St. Paul, MN); Hoffman, Joseph A. (Minneapolis, MN); Lindeman, David D. (Hudson, WI); Noel, Joseph-Robert-Gaetan (St-Hubert, CA); Radewald, Vern E. (Austin, TX); Ranger, Michel (Lachine, CA); Sudano, Anthony (Laval, CA); Trice, Jennifer L. (Eagan, MN); Turgeon, Thomas A. (Fridley, MN)

2000-09-15

345

Variable temperature film and contact resistance measurements on operating n-channel organic thin film transistors  

Microsoft Academic Search

We report structural and electrical properties in thin films of an n-channel organic semiconductor, N,N?-dipentyl-3,4,9,10-perylene tetracarboxylic dimide (PTCDI–C5). The structure of polycrystalline thin films of PTCDI–C5 was studied using x-ray diffraction and atomic force microscopy. Films order with single crystal-like packing, and the direction of ?-? overlap is in the substrate plane. Organic thin film transistors (OTFTs) based on PTCDI–C5

Reid J. Chesterfield; John C. McKeen; Christopher R. Newman; C. Daniel Frisbie; Paul C. Ewbank; Kent R. Mann; Larry L. Miller

2004-01-01

346

High Performance Airbrushed Organic Thin Film Transistors  

SciTech Connect

Spray-deposited poly-3-hexylthiophene (P3HT) transistors were characterized using electrical and structural methods. Thin-film transistors with octyltrichlorosilane treated gate dielectrics and spray-deposited P3HT active layers exhibited a saturation regime mobility as high as 0.1 cm{sup 2} V{sup -1} s{sup -1}, which is comparable to the best mobilities observed in high molecular mass P3HT transistors prepared using other methods. Optical and atomic force microscopy showed the presence of individual droplets with an average diameter of 20 {micro}m and appreciable large-scale film inhomogeneities. Despite these inhomogeneities, near-edge x-ray absorption fine structure spectroscopy of the device-relevant channel interface indicated excellent orientation of the P3HT.

Chan, C.; Richter, L; Dinardo, B; Jaye, C; Conrad, B; Ro, H; Germack, D; Fischer, D; DeLongchamp, D; Gunlach, D

2010-01-01

347

Photoconductivity in thin films of phthalocyanine  

Microsoft Academic Search

The photocurrent and electrolyte electromodulation (EEM) spectra of thin films of metal-free phthalocyanine (H2Pc) and of copper phthalocyanine (CuPc) were investigated. The modulation spectra yielded three distinct features around 1·61,\\u000a 2·30 and 2·93 eV for H2Pc and around 1·63, 2·04 and 3·20 eV for CuPc. The spectral dependence maxima of photoconductivity correspond to the modulation\\u000a spectra. These features are interpreted

Francis P Xavier; George J Goldsmith

1995-01-01

348

Transient thin film laser pyrolysis of RDX  

SciTech Connect

A new experimental technique is described for monitoring initial pyrolysis products in condensed phase energetic materials. Each sample is prepared as a thin film by vapor deposition onto a 77 K substrate and is subsequently pyrolyzed using a pulsed CO{sub 2} laser. Rapid quenching to the substrate temperature traps the initial reaction products, which are detected using transmission FTIR spectroscopy. Fluence dependence studies show that the initial step in thermal decomposition of RDX (1,3,5-triazine) is unimolecular scission of one of the N-N bonds.

Botcher, T.R.; Wight, C.A. [Univ. of Utah, Salt Lake City, UT (United States)

1993-12-31

349

Thin transparent conducting films of cadmium stannate  

Microsoft Academic Search

A process for preparing thin Cd.sub.2 SnO.sub.4 films. The process comprises the steps of RF sputter coating a Cd.sub.2 SnO.sub.4 layer onto a first substrate; coating a second substrate with a CdS layer; contacting the Cd.sub.2 SnO.sub.4 layer with the CdS layer in a water- and oxygen-free environment and heating the first and second substrates and the Cd.sub.2 SnO.sub.4 and

Xuanzhi Wu; Timothy J. Coutts

2001-01-01

350

Thin film photovoltaic device with multilayer substrate  

DOEpatents

A thin film photovoltaic device which utilizes at least one compound semiconductor layer chosen from Groups IIB and VA of the Periodic Table is formed on a multilayer substrate The substrate includes a lowermost support layer on which all of the other layers of the device are formed. Additionally, an uppermost carbide or silicon layer is adjacent to the semiconductor layer. Below the carbide or silicon layer is a metal layer of high conductivity and expansion coefficient equal to or slightly greater than that of the semiconductor layer.

Catalano, Anthony W. (Rushland, PA); Bhushan, Manjul (Wilmington, DE)

1984-01-01

351

Thin-Film Photovoltaic Device Fabrication  

NASA Technical Reports Server (NTRS)

This project will primarily involve the fabrication and characterization of thin films and devices for photovoltaic applications. The materials involved include Il-VI materials such as zinc oxide, cadmium sulfide, and doped analogs. The equipment ot be used will be sputtering and physical evaporations. The types of characterization includes electrical, XRD, SEM and CV and related measurements to establish the efficiency of the devices. The faculty fellow will be involved in a research team composed of NASA and University researchers as well as students and other junior researchers.

Scofield, John H.

2003-01-01

352

Casimir Force between Atomically Thin Gold Films  

E-print Network

We have used density functional theory to calculate the anisotropic dielectric functions for ultrathin gold sheets (composed of 1, 3, 6, and 15 atomic layers). Such films are important components in nano-electromechanical systems. When using correct dielectric functions rather than bulk gold dielectric functions we predict an enhanced attractive Casimir-Lifshitz force (at most around 20%) between two atomically thin gold sheets. For thicker sheets the dielectric properties and the corresponding Casimir forces approach those of gold half-spaces. The magnitude of the corrections that we predict should, within the today's level of accuracy in Casimir force measurements, be clearly detectable.

M. Boström; C. Persson; Bo E. Sernelius

2012-12-03

353

Nanostructured thin films and their macrobehaviors  

NASA Astrophysics Data System (ADS)

The iridescence green band and cyan tail of the wing on Papilio blumei butterfly were investigated. The bi-color phenomenon on the scales of butterfly wings was found and analyzed. The spectral change with thickness of chitin-air layers, width of air hole, total layer numbers and incident angle of light were simulated by FDTD method. 2D photonic-crystal model was applied to explain the change of reflectance spectra and color with angle. The replica of structural color and nanostructured thin films for Papilio blumei butterflies was fabricated successfully by three main techniques, PS spheres bedding, electron-beam gun evaporation and ICP etching.

Lo, Mei-Ling; Liao, Shih-Fang; Lee, Cheng-Chung

2014-08-01

354

Multiscale modeling on cluster deposited thin film  

NASA Astrophysics Data System (ADS)

Thin film composed of magnetic clusters deposited on various substrates has attracted strong attention both as a new manufacturing technique to realize high density magnetic recording media [1] and to create systems with unique magnetic properties. Since the features of films are influenced by the cluster formation process during the flight path, the relevant physical scale to be studied is as large as centimeters. Moreover, since the behavior of segregation processes on the substrate is not negligible, the relevant smallest physical scale is of the order of 1 nm. In this paper a new model of cluster growth and deposition processes based on a combination of Direct Simulation Monte Carlo (DSMC) [2] and Monte Carlo (MC) methods is introduced to examine the effects of cluster deposition conditions on film formation by an adiabatic expansion process. Several types of size distributions of generated clusters under various conditions are obtained by the present model. The results of the simulations show that the size distribution is strongly related to the experimental conditions and in turn the resulting film properties are varied. [1] H. Mizuseki, M. Ishihara, X. Hu, Y. Kawazoe, and N. Ohta, IEEE Trans. Magn. (1996) 4335. [2] H. Mizuseki, Y. Jin, Y. Kawazoe, and Luc T. Wille, J. Appl. Phys., (2000) 6561.

Mizuseki, Hiroshi; Hongo, Kenta; Kawazoe, Yoshiyuki; Wille, Luc T.

2002-03-01

355

Thin film coatings with variable emittance  

NASA Astrophysics Data System (ADS)

The temperature of a nanosatellite in orbit varies strongly as it goes into earth shadow or solar radiation. A variable emittance panel built with an electrochromic material, could improve the temperature control by providing an adaptive thermal control. The active function is due to an electrochromic layer, WO3, deposited by sputtering. Intercalation of Li+ leads to a change in the electron configuration, which modulates the radiation properties. Thin WO3 films were deposited onto Indium Tin Oxide (ITO) coated glass by reactive dc sputtering. IR measurements were done in a Perkin-Elmer 983 spectrophotometer. The IR emittance modulation, (Delta) (epsilon) of WO3 films, deposited on ITO coated glass, has been investigated. The emittance, (epsilon) , is computed from the reflectance, at 25 degrees C. Initial results show emittances in the range from 0.2 to 0.5 crystalline film has (Delta) (epsilon) equals 0.12, and the amorphous film has (Delta) (epsilon) equals 0.3. IR properties of WO3 need to be further investigated as well as the construction of a whole device.

Larsson, Anna-Lena; Niklasson, Gunnar A.; Stenmark, Lars

1999-09-01

356

Evaporated nanostructured Y2O3:Eu thin films.  

PubMed

Europium-doped yttrium oxide (Y2O3:Eu) is a well-known luminescent material that in recent years has been studied in thin-film form. However, to date there has not been a great effort put into altering the nanostructure of these films. A thin-film deposition technique called glancing angle deposition allows for a high degree of control over the nanostructure of the thin film, resulting in thin films with nanostructure geometries ranging from chevron and post to helix. Glancing-angle deposition was used to make europium-doped yttrium oxide thin films with slanted-post nanostructures. Portions of the films were annealed in air at 850 degrees C for 10 hours following deposition. Scanning electron microscopy was used to characterize the nanostructures of the films, while UV laser excitation was used to characterize the photoluminescence properties of the films. The annealed samples exhibited increased photoluminescent responses compared to unannealed samples; however, the porous nanoscale geometry of the films was unaffected. In order to optimize the photoluminescence properties of the films, both the partial pressure of oxygen during film deposition and the level of europium doping in the source material used were varied. Films fabricated from the source material with a greater amount of europium doping had larger photoluminescent responses, while the optimal partial pressure of oxygen during electron-beam evaporation was found to be less than 1.0 x 10(-4) torr. PMID:15853140

Hrudey, P C P; Taschuk, M; Tsui, Y Y; Fedosejevs, R; Sit, J C; Brett, M J

2005-02-01

357

Electrodeposited CulnSe2 Thin Film Junctions  

NASA Technical Reports Server (NTRS)

We have investigated thin films and junctions based on copper indium diselenide (CIS) which have been grown by electrochemical deposition. CIS is a leading candidate for use in polycrystalline thin film photovoltaic solar cells. Electrodeposition is a cost-effective method for producing thin-film CIS. We have produced both p and n type CIS thin films from the same aqueous solution by simply varying the deposition potential. A CIS pn junction was deposited using a step-function potential. Stoichiometry of the single layer films was determined by energy dispersive spectroscopy. Carrier densities of these films increased with deviation from stoichiometry, as determined by the capacitance versus voltage dependence of Schottky contacts. Optical bandgaps for the single layer films as determined by transmission spectroscopy were also found to increase with deviation from stoichiometry. Rectifying current versus voltage characteristics were demonstrated for the Schottky barriers and for the pn junction.

Raffaelle, R. P.; Mantovani, J. G.; Bailey, S. G.; Hepp, A. F.; Gordon, E. M.; Haraway, R.

1998-01-01

358

Photoacid Generation in Thin Films of Chemically Amplified Photoresist  

NASA Astrophysics Data System (ADS)

Pattern formation in thin films of chemically amplified photoresist begins with the generation of an acid catalyst during exposure to light or other forms of radiation. Acid is created by the photolysis or radiolysis of a photoacid generator dispersed within a matrix polymer. Photoacid catalyzes reactions within the film that alter its dissolution rate. An image is formed in the resist film during development by exploiting the difference in dissolution rates of the exposed and unexposed regions. In this work, we illustrate that the process of acid generation in ultra-thin resist films less than 150nm thick exposed to ionizing radiation is affected by the composition of the substrate. We have determined that the concentration of acid required for catalyzing reactions within these ultra-thin films increases as the film thickness decreases. This increased acid requirement explains the increase in exposure dose needed to pattern ultra-thin resist films by ionizing radiation.

Pawloski, Adam; Nealey, Paul

2002-03-01

359

Electrodeposited CuInSe2 Thin Film Junctions  

NASA Technical Reports Server (NTRS)

We have investigated thin films and junctions based on copper indium diselenide (CIS) which have been grown by electrochemical deposition. CIS is a leading candidate for use in polycrystalline thin film photovoltaic solar cells. Electrodeposition is a cost-effective method for producing thin-film CIS. We have produced both p and n type CIS thin films from the same aqueous solution by simply varying the deposition potential. A CIS pn junction was deposited using a step-function potential. Stoichiometry of the single layer films was determined by energy dispersive spectroscopy. Carrier densities of these films increased with deviation from stoichiometry, as determined by the capacitance versus voltage dependence of Schottky contacts. Optical bandgaps for the single layer films as determined by transmission spectroscopy were also found to increase with deviation from stoichiometry. Rectifying current versus voltage characteristics were demonstrated for the Schottky barriers and for the pn junction.

Raffaelle, R. P.; Mantovani, J. G.; Bailey, S. G.; Hepp, A. F.; Gordon, E. M.; Haraway, R.

1997-01-01

360

Method of improving field emission characteristics of diamond thin films  

DOEpatents

A method of preparing diamond thin films with improved field emission properties is disclosed. The method includes preparing a diamond thin film on a substrate, such as Mo, W, Si and Ni. An atmosphere of hydrogen (molecular or atomic) can be provided above the already deposited film to form absorbed hydrogen to reduce the work function and enhance field emission properties of the diamond film. In addition, hydrogen can be absorbed on intergranular surfaces to enhance electrical conductivity of the diamond film. The treated diamond film can be part of a microtip array in a flat panel display. 3 figs.

Krauss, A.R.; Gruen, D.M.

1999-05-11

361

Method of improving field emission characteristics of diamond thin films  

DOEpatents

A method of preparing diamond thin films with improved field emission properties. The method includes preparing a diamond thin film on a substrate, such as Mo, W, Si and Ni. An atmosphere of hydrogen (molecular or atomic) can be provided above the already deposited film to form absorbed hydrogen to reduce the work function and enhance field emission properties of the diamond film. In addition, hydrogen can be absorbed on intergranular surfaces to enhance electrical conductivity of the diamond film. The treated diamond film can be part of a microtip array in a flat panel display.

Krauss, Alan R. (Naperville, IL); Gruen, Dieter M. (Downer Grove, IL)

1999-01-01

362

Cooper pair phase oscillation in thin Al superconductor induced by effective Zeeman splitting from spin injection  

NASA Astrophysics Data System (ADS)

By placing a superconductor (S) and a ferromagnet (F) in close contact, the superconductivity proximity effect induces transient Cooper pairs in F leading to FFLO [1,2] state, while the ferromagnetic proximity effect will populate the S region with non-equilibrium parallel spins. In our experiment, the spins are induced from both sides of the superconductor symmetrically through thin Al2O3 tunnel barriers. By toggling the two F layers between parallel and anti-parallel, we can effectively turn on and off the spin imbalance in the Al layer creating > 1000% MR. The Tc of Al layer is shifted between parallel and antiparallel states as a net result of the non-equilibrium spin population. Such Tc shift is observed to oscillate with Al layer thickness, which is a clear evidence that the effective Zeeman splitting caused by parallel spin population can also induce FFLO states in superconductors. The CPP conductance in such a structure also show dramatic difference between the two states. 1. P. Fulde and R.A. Ferrel, Phys. Rev. 135, A550 (1964) 2. A. I. Larkin and Y. N. Ovchinnikov, Sov. Phys. JEPT 20, 762 (1965)

Miao, Guo-Xing; Nietsch, Jochem; Moodera, Jagadeesh

2007-03-01

363

thin films toward less leakage currents  

NASA Astrophysics Data System (ADS)

To prepare high-density integrated capacitors with low leakage currents, 0.2-?m-thick BaTiO3 thin films were successfully deposited on integrated semiconductor substrates at room temperature by the aerosol deposition (AD) method. In this study, the effects of starting powder size were considered in an effort to remove macroscopic defects. A surface morphology of 25.3 nm and an interface roughness of less than 50 nm were obtained using BT-03B starting powder. The nano-crystalline thin films achieved after deposition were annealed at various temperatures to promote crystallization and densification. Moreover, the influence of rapid thermal annealing process on the surface morphology and crystal growth was evaluated. As the annealing temperature increased from room temperature to 650°C, the root mean square (RMS) roughness decreased from 25.3 to 14.3 nm. However, the surface was transformed into rough performance at 750°C, which agreed well with the surface microstructure trend. Moreover, the crystal growth also reveals the changes in surface morphology via surface energy analysis.

Yao, Zhao; Wang, Cong; Li, Yang; Kim, Hong-Ki; Kim, Nam-Young

2014-08-01

364

Apparatus for laser assisted thin film deposition  

DOEpatents

A pulsed laser deposition apparatus uses fiber optics to deliver visible output beams. One or more optical fibers are coupled to one or more laser sources, and delivers visible output beams to a single chamber, to multiple targets in the chamber or to multiple chambers. The laser can run uninterrupted if one of the deposition chambers ceases to operate because other chambers can continue their laser deposition processes. The laser source can be positioned at a remote location relative to the deposition chamber. The use of fiber optics permits multi-plexing. A pulsed visible laser beam is directed at a generally non-perpendicular angle upon the target in the chamber, generating a plume of ions and energetic neutral species. A portion of the plume is deposited on a substrate as a thin film. A pulsed visible output beam with a high pulse repetition frequency is used. The high pulse repetition frequency is greater than 500 Hz, and more preferably, greater than about 1000 Hz. Diamond-like-carbon (DLC) is one of the thin films produced using the apparatus. 9 figs.

Warner, B.E.; McLean, W. II

1996-02-13

365

Rechargeable thin-film lithium batteries  

SciTech Connect

Rechargeable thin-film batteries consisting of lithium metal anodes, an amorphous inorganic electrolyte, and cathodes of lithium intercalation compounds have been fabricated and characterized. These include Li-TiS{sub 2}, Li-V{sub 2}O{sub 5}, and Li-Li{sub x}Mn{sub 2}O{sub 4} cells with open circuit voltages at full charge of about 2.5 V, 3.7 V, and 4.2 V, respectively. The realization of these robust cells, which can be cycled thousands of times, was possible because of the stability of the amorphous lithium electrolyte, lithium phosphorus oxynitride. This material has a typical composition of Li{sub 2.9}PO{sub 3.3}N{sub 0.46}and a conductivity at 25 C of 2 {mu}S/cm. The thin-film cells have been cycled at 100% depth of discharge using current densities of 5 to 100 {mu}A/cm{sup 2}. Over most of the charge-discharge range, the internal resistance appears to be dominated by the cathode, and the major source of the resistance is the diffusion of Li{sup +} ions from the electrolyte into the cathode. Chemical diffusion coefficients were determined from ac impedance measurements.

Bates, J.B.; Gruzalski, G.R.; Dudney, N.J.; Luck, C.F.; Yu, X.

1993-09-01

366

Thin-film rechargeable lithium batteries  

SciTech Connect

Rechargeable thin-films batteries with lithium metal anodes, an amorphous inorganic electrolyte, and cathodes of lithium intercalation compounds have been fabricated and characterized. The cathodes include TiS{sub 2}, the {omega} phase of V{sub 2}O{sub 5}, and the cubic spinel Li{sub x}Mn{sub 2}O{sub 4} with open circuit voltages at full charge of about 2.5 V, 3.7 V, and 4.2 V, respectively. The development of these robust cells, which can be cycled thousands of times, was possible because of the stability of the amorphous lithium electrolyte, lithium phosphorus oxynitride. This material has a typical composition of Li{sub 2.9}PO{sub 3.3}N{sub 0.46} and a conductivity at 25 C of 2 {mu}S/cm. Thin-film cells have been cycled at 100% depth of discharge using current densities of 2 to 100 {mu}A/cm{sup 2}. The polarization resistance of the cells is due to the slow insertion rate of Li{sup +} ions into the cathode. Chemical diffusion coefficients for Li{sup +} ions in the three types of cathodes have been estimated from the analysis of ac impedance measurements.

Bates, J.B.; Gruzalski, G.R.; Dudney, N.J.; Luck, C.F.; Yu, X.

1993-11-01

367

Characterization of thin-film thickness  

NASA Astrophysics Data System (ADS)

Analysis methods and instrumentation for obtaining optical parameters and thickness profiles of thin-film samples from spectrophotometric and ellipsometric measurements are presented. Measured samples include thermally grown and evaporated SiO2 on a silicon substrate and a polymer photoresist layer on silicon. Experimental results at multiple sample positions give the thickness uniformity and optical constants of thin films. The thickness results obtained with spectrophotometry and ellipsometry agree within 1 nm for the 300 nm thick layer of SiO2 on silicon. For the 1600 nm thick resist sample the agreement of the measurement methods is within 8 nm. For the sample with a nominally 6000 nm thick layer of SiO2 on silicon, there is a deviation of ?100 nm between the spectrophotometry and ellipsometry results. As an application, the optical parameters of a SiO2 layer on an induced junction silicon photodiode are determined by spectrophotometry and are used to confirm earlier values and uncertainties of the SiO2 refractive index and layer thickness non-uniformity.

Pourjamal, Sara; Mäntynen, Henrik; Jaanson, Priit; Rosu, Dana Maria; Hertwig, Andreas; Manoocheri, Farshid; Ikonen, Erkki

2014-12-01

368

Use of thin films in high-temperature superconducting bearings.  

SciTech Connect

In a PM/HTS bearing, locating a thin-film HTS above a bulk HTS was expected to maintain the large levitation force provided by the bulk with a lower rotational drag provided by the very high current density of the film. For low drag to be achieved, the thin film must shield the bulk from inhomogeneous magnetic fields. Measurement of rotational drag of a PM/HTS bearing that used a combination of bulk and film HTS showed that the thin film is not effective in reducing the rotational drag. Subsequent experiments, in which an AC coil was placed above the thin-film HTS and the magnetic field on the other side of the film was measured, showed that the thin film provides good shielding when the coil axis is perpendicular to the film surface but poor shielding when the coil axis is parallel to the surface. This is consistent with the lack of reduction in rotational drag being due to a horizontal magnetic moment of the permanent magnet. The poor shielding with the coil axis parallel to the film surface is attributed to the aspect ratio of the film and the three-dimensional nature of the current flow in the film for this coil orientation.

Hull, J. R.; Cansiz, A.

1999-09-30

369

Structural and Optical Properties of Nanoscale Galinobisuitite Thin Films  

PubMed Central

Galinobisuitite thin films of (Bi2S3)(PbS) were prepared using the chemical bath deposition technique (CBD). Thin films were prepared by a modified chemical deposition process by allowing the triethanolamine (TEA) complex of Bi3+ and Pb2+ to react with S2? ions, which are released slowly by the dissociation of the thiourea (TU) solution. The films are polycrystalline and the average crystallite size is 35 nm. The composition of the films was measured using the atomic absorption spectroscopy (AAS) technique. The films are very adherent to the substrates. The crystal structure of Galinobisuitite thin films was calculated by using the X-ray diffraction (XRD) technique. The surface morphology and roughness of the films were studied using scanning electron microscopes (SEM), transmission electron microscopes (TEM) and stylus profilers respectively. The optical band gaps of the films were estimated from optical measurements. PMID:24473136

Abd-Elkader, Omar H.; Deraz, N. M.

2014-01-01

370

Thermal Sensor Arrays for The Combinatorial Analysis of Thin Films  

E-print Network

Thermal Sensor Arrays for The Combinatorial Analysis of Thin Films A dissertation presented Advisor Author Joost J. Vlassak Patrick J. McCluskey Thermal Sensor Arrays for The Combinatorial Analysis of Thin Films Abstract Membrane-based thermal sensor arrays were developed for the high- throughput

371

Thin film knitting pattern morphology from a miktoarm star terpolymer.  

PubMed

Thin film knitting pattern from a miktoarm star terpolymer is demonstrated. Such structures have been predicted but not observed in bulk or thin film form. The knitting pattern exhibits well organized periodic structures consisting of undulating lamellae and alternating cylinders, with well-defined defects that result in sharp 90° bends and T junctions. PMID:24469920

Choi, Hong Kyoon; Nunns, Adam; Sun, Xue Yin; Manners, Ian; Ross, Caroline A

2014-04-23

372

Interface engineered multifunctional oxide thin films with optimized properties  

Microsoft Academic Search

In our world today, energy has become one of the most valuable resources, in particular, renewable and clean energy sources. The research presented here represents an investigation into three separate areas of this topic. In thin film applications, the ordered structures as well as the inherent thinness of the films precludes the normal physics found in bulk materials. Characterizations of

Gregory Roy Collins

2010-01-01

373

Tools to Synthesize the Learning of Thin Films  

ERIC Educational Resources Information Center

After a review of textbooks written for undergraduate courses in physics, we have found that discussions on thin films are mostly incomplete. They consider the reflected and not the transmitted light for two instead of the four types of thin films. In this work, we complement the discussion in elementary textbooks, by analysing the phase…

Rojas, Roberto; Fuster, Gonzalo; Slusarenko, Viktor

2011-01-01

374

AFRL thin-film photovoltaics DSX and roadrunner flight experiments  

Microsoft Academic Search

Thin-film solar cells offer great promise for increasing the capability of future spacecraft. While their efficiencies are low compared to state of the art crystalline solar cells, they have unique attributes that make them very attractive for space use. These attributes include flexibility, low mass, and low cost production. The attractive attributes of thin-film solar cells will go untapped until

P. Hausgen; J. E. Granata; P. Tlomak; J. Jones; S. Enger; B. Zuckermandel

2005-01-01

375

Thin-film zero-group-velocity Lamb wave resonator  

NASA Astrophysics Data System (ADS)

A concept for the development of thin film micro-acoustic resonators is demonstrated. The basic principles for the design and fabrication of zero-group-velocity Lamb acoustic wave resonators on c-textured thin aluminum nitride films are presented. The experimental results demonstrate that the zero-group-velocity waves can be employed in high frequency resonators with small form factors.

Yantchev, Ventsislav; Arapan, Lilia; Katardjiev, Ilia; Plessky, Victor

2011-07-01

376

Transition noise spectral measurements in thin film media  

Microsoft Academic Search

Noise in thin film media is concentrated at the transition center and must be characterized by a nonstationary autocorrelation function. The noise voltage spectrum is determined by the frequency response of this correlation function beyond the standard head field terms. In this work, the use of spectral measurement to determine the nonstationary noise is illustrated. Noise spectra of thin film

Gang Herbert Lin; H. Neal Bertram

1994-01-01

377

Experimental studies of noise autocorrelation in thin film media  

Microsoft Academic Search

Noise voltage autocorrelation in thin film media has been experimentally studied in the time domain. Unlike a spectral measurement, the time domain noise autocorrelation function provides a good characterization of nonstationary noise that is particularly useful for thin film media. A measurement technique is developed to eliminate the noise due to the lack of noise-free timing reference. An empirical eigenfunction

G. H. Lin; H. N. Bertram

1993-01-01

378

Applications of thin film thermocouples for surface temperature measurement  

NASA Astrophysics Data System (ADS)

Thin film thermocouples provide a minimally intrusive means of measuring surface temperature in hostile, high temperature environments. Unlike wire thermocouples, thin films do not necessitate any machining of the surface, therefore leaving intact its structural integrity. Thin films are many orders of magnitude thinner than wire, resulting in less disruption to the gas flow and thermal patterns that exist in the operating environment. Thin film thermocouples have been developed for surface temperature measurement on a variety of engine materials. The sensors are fabricated in the NASA Lewis Research Center's Thin Film Sensor Lab, which is a class 1000 clean room. The thermocouples are platinum-13 percent rhodium versus platinum and are fabricated by the sputtering process. Thin film-to-leadwire connections are made using the parallel-gap welding process. Thermocouples have been developed for use on superalloys, ceramics and ceramic composites, and intermetallics. Some applications of thin film thermocouples are: temperature measurement of space shuttle main engine turbine blade materials, temperature measurement in gas turbine engine testing of advanced materials, and temperature and heat flux measurements in a diesel engine. Fabrication of thin film thermocouples is described. Sensor durability, drift rate, and maximum temperature capabilities are addressed.

Martin, Lisa C.; Holanda, Raymond

1994-08-01

379

Applications of thin-film thermocouples for surface temperature measurement  

NASA Astrophysics Data System (ADS)

Thin film thermocouples provide a minimally intrusive means of measuring surface temperature in hostile, high temperature environments. Unlike wire thermocouples, thin films do not necessitate any machining of the surface, thereby leaving intact its structural integrity. Thin films are many orders of magnitude thinner than wire, resulting in less disruption to the gas flow and thermal patterns that exist in the operating environment. Thin film thermocouples have been developed for surface temperature measurement on a variety of engine materials. The sensors are fabricated in the NASA Lewis Research Center's Thin Film Sensor Lab, which is a Class 1000 Clean Room. The thermocouples are platinum-13% rhodium vs platinum and are fabricated by the sputtering process. Thin film-to-leadwire connections are made using the parallel-gap welding process. Thermocouples have been developed for use on superalloys, ceramics and ceramic composites, and intermetallics. Some applications of thin film thermocouples are: temperature measurement of Space Shuttle Main Engine turbine blade materials, temperature measurement in gas turbine engine testing of advanced materials, and temperature and heat flux measurements in a diesel engine. Fabrication of thin film thermocouples is described. Sensor durability, drift rate, and maximum temperature capabilities are addressed.

Martin, Lisa C.; Holanda, Raymond

1994-10-01

380

A survey of thin-film solar photovoltaic industry & technologies  

E-print Network

A new type of solar cell technology using so-called thin-film solar photovoltaic material has the potential to make a great impact on our lives. Because it uses very little or no silicon at all, thin- film (TF) solar ...

Grama, Sorin

2007-01-01

381

Piezoreslstive graphite/polyimide thin films for micromachining applications  

E-print Network

Piezoreslstive graphite/polyimide thin films for micromachining applications A. Bruno Frazier) In this work, graphite/polyimide composite thin films are introduced and characterized for micromachining applications. The material consists of submicron-sized graphite particles suspended in a benzophenone

382

Thermal conductivity measurements of thin-film resist Dachen Chua)  

E-print Network

Thermal conductivity measurements of thin-film resist Dachen Chua) Solid State and Photonics out-of-plane and in-plane thermal conductivity of thin resist films following different exposure conditions. An optical thermoreflectance technique was used to characterize out-of-plane thermal conductivity

Pease, R. Fabian W.

383

Narrow track recording characteristics in thin film media  

Microsoft Academic Search

In this paper, we report a combined spin-stand measurement and micromagnetic simulation study on narrow track recording characteristics in thin film media. It is found that the onset recording density of nonlinear partial erasure is determined by intertransition percolations near the track edges where the head field gradient is poor. Trimming into the shared pole in merged MR\\/thin film heads

Jian-Gang Zhu; Terence Lam; Hao Fang; T. Chang; Hua-Ching Tong; R. Rottmayer

1997-01-01

384

Nanoengineered Thin Films for Solid Oxide Fuel Cells  

E-print Network

and lattice strain. Fifth, Two-phase (Ce0.9Gd0.1O1.95)0.5/(Zr0.92Y0.08O1.96)0.5 nanocomposite thin films with vertically aligned structure are grown as the electrolyte for thin film solid oxide fuel cells (TFSOFCs). More than 50% increase in overall power...

Su, Qing

2013-11-21

385

STABILITY OF AMORPHOUS SILICON THIN FILM TRANSISTORS AND CIRCUITS  

E-print Network

STABILITY OF AMORPHOUS SILICON THIN FILM TRANSISTORS AND CIRCUITS Ting Liu A DISSERTATION PRESENTED by Ting Liu. All rights reserved #12;Abstract i Hydrogenated amorphous silicon thin-film transistors (a to the breaking of weak bonds in the amorphous silicon. It can be modeled with a "unified stretched exponential

386

CHARACTERIZATION OF URANIUM, URANIUM OXIDE AND SILICON MULTILAYER THIN FILMS  

E-print Network

CHARACTERIZATION OF URANIUM, URANIUM OXIDE AND SILICON MULTILAYER THIN FILMS by David T. Oliphant. Woolley Dean, College of Physical and Mathematical Sciences #12;ABSTRACT CHARACTERIZATION OF URANIUM, URANIUM OXIDE AND SILICON MULTILAYER THIN FILMS David T. Oliphant Department of Physics and Astronomy

Hart, Gus

387

Effective viscosities in thin ionic micellar liquid films  

SciTech Connect

Thin liquid films stabilized by surfactants above the critical micelle concentration exhibit stratification or stepwise dynamic thinning. A continuum hydrodynamic model is outlined for stepwise film thinning that incorporates equilibrium micellar structuring through self-consistent oscillatory disjoining pressures and effective viscosities. Effective viscosities as functions of thickness are evaluated with an extension of the local average density model, considering dilute colloidal suspension shear viscosities and solvent effects. To establish local shear viscosities, structured DFT micellar profiles, coarse-grained densities, and disjoining pressure are used. Ionic micelles and other colloidal systems with repulsive interactions show structured effective viscosities that are generally less than the corresponding homogeneous solution shear viscosity, bounded by the pure solvent viscosity and that of the bulk micellar solution. For 0.1 and 0.2-M sodium dodecylsulfate micellar solutions, the effective viscosities are less than 5 and 10%, respectively, below the homogeneous fluid viscosity, except at small thicknesses, indicating that the micellar film thins faster than a pure water film of the same thickness. Calculated thinning curves closely resemble experimental observations in the stepwise thinning behavior, displaying decreasing slopes and increased step durations at later times. Despite the micellar structuring within the film, the ionic micelles do not contribute appreciably to the viscous resistance of the thinning film. Rather, Reynolds` film thinning is obeyed, with the equilibrium oscillatory disjoining pressures driving the step-wise dynamics. The shear viscosity of the ionic micellar film is well approximated by that of the bulk solution.

Pollard, M.L.; Radke, C.J. [Lawrence Berkeley Lab., CA (United States)] [Lawrence Berkeley Lab., CA (United States)

1996-07-01

388

Impulse photoconductance of thin-film polycrystalline silicon  

Microsoft Academic Search

Using optoelectronic correlation and sampling oscilloscope techniques we measured impulse photoconductance of polycrystalline-Si thin-film photoconductors excited by femtosecond dye-laser pulses. We studied as-deposited micrograin films as well as annealed, H-passivated, and H-passivated\\/annealed films. Results yielded photoexcited carrier mobilities of 6.8 and 104 cm2\\/V s, respectively in as-deposited and 1150 °C-annealed films. The photoconductance decays of as-deposited films showed an initial

R. B. Hammond; N. M. Johnson

1986-01-01

389

Impulse photoconductance of thin-film polycrystalline silicon  

Microsoft Academic Search

Using optoelectronic correlation and sampling oscilloscope techniques, the impulse photoconductance of polycrystalline-Si thin-film photoconductors excited by femtosecond dye-laser pulses were measured. As-deposited micrograin films as well as annealed, H-passivated, and H-passivated\\/annealed films were studied. Results yielded photoexcited carrier mobilities of 6.8 and 104 sq cm\\/V s, respectively in as-deposited and 1150 C-annealed films. The photoconductance decays of as-deposited films showed

R. B. Hammond; N. M. Johnson

1986-01-01

390

Development of a thin film solid state gaseous HCl sensor  

NASA Technical Reports Server (NTRS)

The selection of materials to develop a thin film HCl sensor is discussed. Data were primarily concerned with chemical and physical properties of the film and with electrical properties which exhibit and enhance electrical response when HCl is absorbed on the film surface. Techniques investigated for enhancing electrical response include changing conditions for growing films, adding impurities to the film, changing ambient light intensity, and altering the ambient temperature of the sensing element.

1975-01-01

391

Anomalies of piezoelectric coefficients in barium titanate thin films  

NASA Astrophysics Data System (ADS)

Modeling of electromechanical devices involves the use of different material coefficients, whose measurement is a difficult task, especially when the problem concerns thin films. Required coefficients of thin films could be found theoretically, using known values of the bulk constants. Electromechanical coefficients of barium titanate thin films are still unknown; therefore, it is expedient to carry out their calculations. We give here the full set of electromechanical coefficients of barium titanate thin films for the whole range of technologically available misfit strains. In the present paper, piezoelectric coefficients as functions of a misfit strain were calculated. It was revealed that piezoelectric coefficients exhibit anomalies at phase boundaries and inside the monoclinic r-phase as well. The obtained results allow finding the required values of the thin-film parameters, varying the misfit strain.

Shirokov, Vladimir; Kalinchuk, Valery; Shakhovoy, Roman; Yuzyuk, Yury

2014-11-01

392

Development of Thin-Film Battery Powered Transdermal Medical Devices  

SciTech Connect

Research carried out at ORNL has led to the development of solid state thin-film rechargeable lithium and lithium-ion batteries. These unique devices can be fabricated in a variety of shapes and to any required size, large or small, on virtually any type of substrate. Because they have high energies per unit of volume and mass and because they are rechargeable, thin-film lithium batteries have potentially many applications as small power supplies in consumer and special electronic products. Initially, the objective of this project was to develop thin-film battery powered products. Initially, the objective of this project was to develop thin-film battery powered transdermal electrodes for recording electrocardiograms and electroencephalograms. These ''active'' electrode would eliminate the effect of interference and improve the reliability in diagnosing heart or brain malfunctions. Work in the second phase of this project was directed at the development of thin-film battery powered implantable defibrillators.

Bates, J.B.; Sein, T.

1999-07-06

393

Tailoring Thin Film-Lacquer Coatings for Space Application  

NASA Technical Reports Server (NTRS)

Thin film coatings have the capability of obtaining a wide range of thermal radiative properties, but the development of thin film coatings can sometimes be difficult and costly when trying to achieve highly specular surfaces. Given any space mission's thermal control requirements, there is often a need for a variation of solar absorptance (Alpha(s)), emittance (epsilon) and/or highly specular surfaces. The utilization of thin film coatings is one process of choice for meeting challenging thermal control requirements because of its ability to provide a wide variety of Alpha(s)/epsilon ratios. Thin film coatings' radiative properties can be tailored to meet specific thermal control requirements through the use of different metals and the variation of dielectric layer thickness. Surface coatings can be spectrally selective to enhance radiative coupling and decoupling. The application of lacquer to a surface can also provide suitable specularity for thin film application without the cost and difficulty associated with polishing.

Peters, Wanda C.; Harris, George; Miller, Grace; Petro, John

1998-01-01

394

Physical properties in thin films of iron oxides.  

SciTech Connect

We have grown hematite ({alpha}-Fe{sub 2}O{sub 3}) thin films on stainless steel substrates and magnetite (Fe{sub 3}O{sub 4}) thin films on (0 0 1)-Si single crystal substrates by a RF magnetron sputtering process. {alpha}-Fe{sub 2}O{sub 3} thin films were grown in an Ar atmosphere at substrate temperatures around 400 C, and Fe{sub 3}O{sub 4} thin films in an Ar/O{sub 2} reactive atmosphere at substrate temperatures around 500 C. Conversion electron Moessbauer (CEM) spectra of {alpha}-Fe{sub 2}O{sub 3} thin films exhibit values for hyperfine parameter characteristic of the hematite stoichiometric phase in the weak ferromagnetic state [R.E. Vandenberghe, in: Moessbauer Spectroscopy and Applications in Geology, University Gent, Belgium, 1990. [1

Uribe, J. D.; Osorio, J.; Barrero, C. A.; Girata, D.; Morales, A. L.; Hoffmann, A.; Materials Science Division; Univ. de Antioquia

2008-01-01

395

Chemical bath deposition of crystalline ZnS thin films  

NASA Astrophysics Data System (ADS)

Crystalline zinc sulfide (ZnS) thin films were prepared by chemical bath deposition (CBD) using the mixed aqueous solutions of zinc acetate, thiourea and tri-sodium citrate, where tri-sodium citrate was used as the complexing agent. The thin films were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM) and optical absorption. The as-deposited thin films were surface homogeneous with pure wurtzite structure and the optical band gap of the film was estimated to be 3.53 eV.

Cheng, Jie; Fan, Dong Bo; Wang, Hao; Liu, Bing Wei; Cai Zhang, Yong; Yan, Hui

2003-07-01

396

Method of producing solution-derived metal oxide thin films  

DOEpatents

A method of preparing metal oxide thin films by a solution method. A .beta.-metal .beta.-diketonate or carboxylate compound, where the metal is selected from groups 8, 9, 10, 11, and 12 of the Periodic Table, is solubilized in a strong Lewis base to form a homogeneous solution. This precursor solution forms within minutes and can be deposited on a substrate in a single layer or a multiple layers to form a metal oxide thin film. The substrate with the deposited thin film is heated to change the film from an amorphous phase to a ceramic metal oxide and cooled.

Boyle, Timothy J. (Albuquerque, NM); Ingersoll, David (Albuquerque, NM)

2000-01-01

397

Superconducting Properties of Ion-Implanted Gold - Thin Films.  

NASA Astrophysics Data System (ADS)

The superconducting properties of thin Au _{x}rm Si_{1-x} films prepared by ion beam implantation and ion beam mixing are studied. The films are prepared by evaporation of single Au layers on Si substrates and mixing them with Si, Ar, or Xe, or by Xe beam mixing of alternate multilayers of Au and Si sputtered on rm Al_2 O_3 substrates. The superconducting transition temperature and upper critical fields are determined by measuring the temperature and magnetic field dependence of resistivity. Temperatures as low as 20mK and magnetic fields as high as 8 T were used. Superconductivity in these films is discussed in connection with metastable metallic phases that are reportedly produced in the Au -Si system by high quenching rate preparation techniques like quenching from the vapor or the melt or ion implantation. Preliminary structural studies provide evidence for the existence of these phases and near-edge X-ray absorption and X-ray photoelectron spectroscopy measurements indicate a metallic type of bonding from which compound formation is inferred. The quality of the films is strongly dependent on the conditions of implantation. The maximum superconducting transition temperature attained is about 1.2 K. The upper critical fields have a maximum of 6T. An unusual double transition in the field dependence of resistivity is observed at low temperatures. The effect is very pronounced at compositions near x = 0.5 where the maximum T_{c} occurs. A model is presented to explain this result which invokes the properties of the metastable metallic phases and assumes the formation of more than two such phases in the same sample as the implantation dose increases. The Si-Au interface plays an important role in understanding the model and in interpreting the results of this thesis in general. The origin of superconductivity in the Au -Si system is discussed by relating the experimental results to the various mechanisms suggested in the literature. The implications of the study of this system for the new high T_{c} oxide superconductors are also discussed.

Jisrawi, Najeh Mohamed

398

Oxynitride Thin Film Barriers for PV Packaging  

SciTech Connect

Dielectric thin-film barrier and adhesion-promoting layers consisting of silicon oxynitride materials (SiOxNy, with various stoichiometry) were investigated. For process development, films were applied to glass (TCO, conductive SnO2:F; or soda-lime), polymer (PET, polyethylene terephthalate), aluminized soda-lime glass, or PV cell (a-Si, CIGS) substrates. Design strategy employed de-minimus hazard criteria to facilitate industrial adoption and reduce implementation costs for PV manufacturers or suppliers. A restricted process window was explored using dilute compressed gases (3% silane, 14% nitrous oxide, 23% oxygen) in nitrogen (or former mixtures, and 11.45% oxygen mix in helium and/or 99.999% helium dilution) with a worst-case flammable and non-corrosive hazard classification. Method employed low radio frequency (RF) power, less than or equal to 3 milliwatts per cm2, and low substrate temperatures, less than or equal to 100 deg C, over deposition areas less than or equal to 1000 cm2. Select material properties for barrier film thickness (profilometer), composition (XPS/FTIR), optical (refractive index, %T and %R), mechanical peel strength and WVTR barrier performance are presented.

Glick, S. H.; delCueto, J. A.; Terwilliger, K. M.; Jorgensen, G. J.; Pankow, J. W.; Keyes, B. M.; Gedvilas, L. M.; Pern, F. J.

2005-11-01

399

Controlled nanostructuration of polycrystalline tungsten thin films  

SciTech Connect

Nanostructured tungsten thin films have been obtained by ion beam sputtering technique stopping periodically the growing. The total thickness was maintained constant while nanostructure control was obtained using different stopping periods in order to induce film stratification. The effect of tungsten sublayers' thicknesses on film composition, residual stresses, and crystalline texture evolution has been established. Our study reveals that tungsten crystallizes in both stable {alpha}- and metastable {beta}-phases and that volume proportions evolve with deposited sublayers' thicknesses. {alpha}-W phase shows original fiber texture development with two major preferential crystallographic orientations, namely, {alpha}-W<110> and unexpectedly {alpha}-W<111> texture components. The partial pressure of oxygen and presence of carbon have been identified as critical parameters for the growth of metastable {beta}-W phase. Moreover, the texture development of {alpha}-W phase with two texture components is shown to be the result of a competition between crystallographic planes energy minimization and crystallographic orientation channeling effect maximization. Controlled grain size can be achieved for the {alpha}-W phase structure over 3 nm stratification step. Below, the {beta}-W phase structure becomes predominant.

Girault, B. [Institut P' (UPR 3346 CNRS), Universite de Poitiers, ENSMA, Bd Pierre et Marie Curie, 86962 Futuroscope Cedex (France); Institut de Recherche en Genie Civil et Mecanique (UMR CNRS 6183), LUNAM Universite, Universite de Nantes, Centrale Nantes, CRTT, 37 Bd de l'Universite, BP 406, 44602 Saint-Nazaire Cedex (France); Eyidi, D.; Goudeau, P.; Guerin, P.; Bourhis, E. Le; Renault, P.-O. [Institut P' (UPR 3346 CNRS), Universite de Poitiers, ENSMA, Bd Pierre et Marie Curie, 86962 Futuroscope Cedex (France); Sauvage, T. [CEMHTI/CNRS (UPR 3079 CNRS), Universite d'Orleans, 3A rue de la Ferollerie, 45071 Orleans Cedex 2 (France)

2013-05-07

400

Vertically aligned biaxially textured molybdenum thin films  

SciTech Connect

Vertically aligned, biaxially textured molybdenum nanorods were deposited using dc magnetron sputtering with glancing flux incidence (alpha = 85 degrees with respect to the substrate normal) and a two-step substrate-rotation mode. These nanorods were identified with a body-centered cubic crystal structure. The formation of a vertically aligned biaxial texture with a [110] out-of-plane orientation was combined with a [-110] in-plane orientation. The kinetics of the growth process was found to be highly sensitive to an optimum rest time of 35 seconds for the two-step substrate rotation mode. At all other rest times, the nanorods possessed two separate biaxial textures each tilted toward one flux direction. While the in-plane texture for the vertical nanorods maintains maximum flux capture area, inclined Mo nanorods deposited at alpha = 85 degrees without substrate rotation display a [-1-1-4] in-plane texture that does not comply with the maximum flux capture area argument. Finally, an in situ capping film was deposited with normal flux incidence over the biaxially textured vertical nanorods resulting in a thin film over the porous nanorods. This capping film possessed the same biaxial texture as the nanorods and could serve as an effective substrate for the epitaxial growth of other functional materials.

Krishnan, Rahul [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Riley, Michael [Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Lee, Sabrina [US Army Armament Research, Development and Engineering Center, Benet Labs, Watervliet, New York 12189 (United States); Lu, Toh-Ming [Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

2011-09-15

401

Single crystalline film on glass for thin film solar cells.  

PubMed

A simple Ge-on-glass metal-oxide-semiconductor solar cell has been demonstrated by wafer bonding and smart-cut. Since single crystalline Ge is directly bonded on glass, the crystalline substrate is not necessary. The metal-oxide-semiconductor structure can be easily fabricated without n and p dopant diffusion or implantation. The reason for low efficiency is discussed, and then the optimized structures are designed by simulation. An outstanding enhancement on efficiency can be achieved with the Si/Ge/Si structure. The best performance can be achieved by optimization of the position of the Ge layer, the thickness of the Ge layer, and the number of the Ge layers. The efficiency of the thin film Si/Ge/Si solar cell with single layer of 30-nm-thick Ge outside the depletion region reaches 15.9%, as compared to the control Si sample of 11.8%. Based on the simulation and technologies, high efficiency thin film solar cells can be demonstrated in the future. PMID:19504892

Lin, C H; Yang, Y J; Encinas, E; Chen, W Y; Tsai, J J; Liu, C W

2009-06-01

402

Thermally induced optical nonlinearity during transient heating of thin films  

NASA Astrophysics Data System (ADS)

This work studies the temperature field and the optical response of weakly absorbing thin films with thermally induced optical nonlinearity during picosecond to nanosecond pulsed-laser heating. A one-dimensional model is presented that examines the effects of the temperature dependent optical constants and the nonuniform absorption caused by interference. The energy equation is solved numerically, coupled with the matrix method in optical multilayer theory. Both cadmium sulfide (CdS) thin films and a zinc selenide (ZnSe) interference filter are considered. The computational results compare favorably with available experimental data on the ZnSe interference filter. This study shows that the transient temperature distributions in the films are highly nonuniform. Such nonuniformity yields Airy's formulae for calculating the thin-film reflectance and transmittance inapplicable. Applications of the work include optical bistability, localized change of the film structure, and measurement of the thermal diffusivity of thin films.

Chen, G.; Tien, C. L.

1994-05-01

403

Characterization of reliability of printed indium tin oxide thin films.  

PubMed

Recently, decreasing the amount of indium (In) element in the indium tin oxide (ITO) used for transparent conductive oxide (TCO) thin film has become necessary for cost reduction. One possible approach to this problem is using printed ITO thin film instead of sputtered. Previous studies showed potential for printed ITO thin films as the TCO layer. However, nothing has been reported on the reliability of printed ITO thin films. Therefore, in this study, the reliability of printed ITO thin films was characterized. ITO nanoparticle ink was fabricated and printed onto a glass substrate followed by heating at 400 degrees C. After measurement of the initial values of sheet resistance and optical transmittance of the printed ITO thin films, their reliabilities were characterized with an isothermal-isohumidity test for 500 hours at 85 degrees C and 85% RH, a thermal shock test for 1,000 cycles between 125 degrees C and -40 degrees C, and a high temperature storage test for 500 hours at 125 degrees C. The same properties were investigated after the tests. Printed ITO thin films showed stable properties despite extremely thermal and humid conditions. Sheet resistances of the printed ITO thin films changed slightly from 435 omega/square to 735 omega/square 507 omega/square and 442 omega/square after the tests, respectively. Optical transmittances of the printed ITO thin films were slightly changed from 84.74% to 81.86%, 88.03% and 88.26% after the tests, respectively. These test results suggest the stability of printed ITO thin film despite extreme environments. PMID:24245331

Hong, Sung-Jei; Kim, Jong-Woong; Jung, Seung-Boo

2013-11-01

404

Template engineering of Co-doped BaFe2As2 single-crystal thin films.  

PubMed

Understanding new superconductors requires high-quality epitaxial thin films to explore intrinsic electromagnetic properties and evaluate device applications. So far, superconducting properties of ferropnictide thin films seem compromised by imperfect epitaxial growth and poor connectivity of the superconducting phase. Here we report new template engineering using single-crystal intermediate layers of (001) SrTiO(3) and BaTiO(3) grown on various perovskite substrates that enables genuine epitaxial films of Co-doped BaFe(2)As(2) with a high transition temperature (T(c,rho=0) of 21.5 K, where rho=resistivity), a small transition width (DeltaT(c)=1.3 K), a superior critical current density J(c) of 4.5 MA cm(-2) (4.2 K) and strong c-axis flux pinning. Implementing SrTiO(3) or BaTiO(3) templates to match the alkaline-earth layer in the Ba-122 with the alkaline-earth/oxygen layer in the templates opens new avenues for epitaxial growth of ferropnictides on multifunctional single-crystal substrates. Beyond superconductors, it provides a framework for growing heteroepitaxial intermetallic compounds on various substrates by matching interfacial layers between templates and thin-film overlayers. PMID:20190768

Lee, S; Jiang, J; Zhang, Y; Bark, C W; Weiss, J D; Tarantini, C; Nelson, C T; Jang, H W; Folkman, C M; Baek, S H; Polyanskii, A; Abraimov, D; Yamamoto, A; Park, J W; Pan, X Q; Hellstrom, E E; Larbalestier, D C; Eom, C B

2010-05-01

405

Photon down-conversion in Terbium(III)-doped thin dielectric films and fluorozirconate glasses for thin film solar cells  

Microsoft Academic Search

The efficiency of thin film solar cells can be improved with the addition of a photon down-conversion top layer. This layer converts incident ultraviolet light of the solar spectrum to visible light, which transmits through the glass and is efficiently absorbed by the active layer of the solar cell. The results of our investigations of thin dielectric films and fluorozirconate

K. Baumgartner; B. Ahrens; O. Angelov; M. Sendova-Vassileva; D. Dimova-Malinovska; B. Holländer; S. Schweizer; R. Carius

2010-01-01

406

Characterization of oxide thin films using optical techniques  

Microsoft Academic Search

Thin films of oxide materials are playing a growing role as critical elements in optoelectronic devices and nanoscale devices. In this work, thin films of some typical oxides such as WO3, Ga2O3 and SrTiO3 were investigated. We present measurements of those films, using various optical techniques like photoconductivity transients over a wide time range and photo-Hall measurements. Analysis of the

J. H. Hao; J. Gao

2006-01-01

407

Structural and photoluminescent properties of TiN thin films  

NASA Astrophysics Data System (ADS)

Structural and photoluminescent properties of TiN thin films deposited by dc reactive magnetron sputtering are studied. It is found that TiN thin films are polycrystalline with a grain size of ˜15 nm and have a NaCl-type cubic crystal structure with a lattice constant of 0.42 nm. The TiN films under study exhibit photoluminescence in the spectral range h ? ? 2.1-3.4 eV at 300 K.

Solovan, M. N.; Brus, V. V.; Maryanchuk, P. D.; Fodchuk, I. M.; Lorents, V. M.; Sletov, A. M.; Sletov, M. M.; Gluba, M.

2014-11-01

408

Thin film adhesion by nanoindentation-induced superlayers. Final report  

SciTech Connect

This work has analyzed the key variables of indentation tip radius, contact radius, delamination radius, residual stress and superlayer/film/interlayer properties on nanoindentation measurements of adhesion. The goal to connect practical works of adhesion for very thin films to true works of adhesion has been achieved. A review of this work titled ''Interfacial toughness measurements of thin metal films,'' which has been submitted to Acta Materialia, is included.

Gerberich, William W.; Volinsky, A.A.

2001-06-01

409

Photolithography I: Thin Film Deposition and Mask Design  

NSDL National Science Digital Library

In this lab, students design, fabricate and test four Al resistors using some of the techniques that are employed to make integrated circuits. First, students will evaporate a thin film of aluminum on a Si wafer. Then, they will use photolithographic techniques to pattern the film and etch away unwanted parts, leaving only your resistors. Students will complete the Al thin film deposition and mask design parts of the process. For the second part of this laboratory activity, click here.

Buhrman, Robert A.; Huang, Kevin; Plisch, Monica; Shull, Alison

2008-10-16

410

Investigating the nanostructured gold thin films using the multifractal analysis  

NASA Astrophysics Data System (ADS)

The atomic force microscopy images representing the surface morphology of the nanostructured gold thin films of thickness of 20, 50 and 200 nm, respectively, were investigated using the multifractal analysis. The interface width and growth exponent corresponding to films of different thicknesses were estimated. The surfaces having greater roughness give rise to larger nonlinearity and wider width of the multifractal spectrum. The statistical tests confirm that the gold thin film surfaces under investigation are multifractal in nature.

Yadav, R. P.; Singh, U. B.; Mittal, A. K.; Dwivedi, S.

2014-12-01

411

Crystalline structure of chemically deposited thallium sulfide thin films  

Microsoft Academic Search

Thin film coatings of Tl4S3 or Tl2S of 100–750 nm in thickness have been deposited from a mixture of citratothallium complex and thiourea solutions at 35 or 50°C by chemical bath deposition on glass substrates coated with a thin ZnS film. Upon heating in a nitrogen atmosphere at 300°C, all the films, irrespective of the initial composition, convert to crystalline

V. Estrella; M. T. S Nair; P. K Nair

2002-01-01

412

Thin film coatings for space electrical power system applications  

NASA Technical Reports Server (NTRS)

This paper examines some of the ways in which thin film coatings can play a role in aerospace applications. Space systems discussed include photovoltaic and solar dynamic electric power generation systems, including applications in environmental protection, thermal energy storage, and radiator emittance enhancement. Potential applications of diamondlike films to both atmospheric and space based systems are examined. Also, potential uses of thin films of the recently discovered high-temperature superconductive materials are discussed.

Gulino, Daniel A.

1988-01-01

413

Thin film coatings for space electrical power system applications  

NASA Technical Reports Server (NTRS)

This paper examines some of the ways in which thin film coatings can play a role in aerospace applications. Space systems discussed include photovoltaic and solar dynamic electric power generation systems, including applications in environmental protection, thermal energy storage, and radiator emittance enhancement. Potential applications of diamondlike films to both atmospheric and space based systems are examined. Also, potential uses of thin films of the recently discovered high-temperature superconductive materials are discussed.

Gulino, Daniel A.

1989-01-01

414

Uniaxial anisotropy in magnetite thin film—Magnetization studies  

Microsoft Academic Search

Magnetization and electrical resistivity measurements have been performed on a stoichiometric single crystalline magnetite Fe3O4 thin film (thickness of ca. 500nm) MBE deposited on MgO (100) substrate. The aim of these studies was to check the influence of preparation method and sample form (bulk vs. thin film) on magnetic anisotropy properties in magnetite. The film magnetization along ?001? versus applied

A. Wiechec; J. Korecki; B. Handke; Z. Kakol; D. Owoc; D. A. Antolak; A. Kozlowski

2006-01-01

415

Hall effect in Fe$_3$O$_4$ epitaxial thin films  

Microsoft Academic Search

Magnetite epitaxial thin films have been prepared by pulsed laser deposition at 340 C on MgO and Si substrates. One key result is that the thin film properties are almost identical to the properties of bulk material. For 40 - 50 nm thick films, the saturation magnetization and conductivity are respectively 453 emu\\/cm^3 and 225 1\\/(Ohm cm) at room temperature.

D. Reisinger; P. Majewski; M. Opel; L. Alff; R. Gross

2004-01-01

416

Integrated thin film cadmium sulfide solar cell module  

NASA Technical Reports Server (NTRS)

The design, development, fabrication and tests of flexible integrated thin-film cadmium sulfide solar cells and modules are discussed. The development of low cost and high production rate methods for interconnecting cells into large solar arrays is described. Chromium thin films were applied extensively in the deposited cell structures as a means to: (1) achieve high adherence between the cadmium sulfide films and the vacuum-metallized copper substrates, (2) obtain an ohmic contact to the cadmium sulfide films, and (3) improve the adherence of gold films as grids or contact areas.

Mickelsen, R. A.; Abbott, D. D.

1971-01-01

417

Effect of current injection into thin-film Josephson junctions  

NASA Astrophysics Data System (ADS)

New thin-film Josephson junctions have recently been tested in which the current injected into one of the junction banks governs Josephson phenomena. One thus can continuously manage the phase distribution at the junction by changing the injected current. A method of calculating the distribution of injected currents is proposed for a half-infinite thin-film strip with source-sink points at arbitrary positions at the film edges. The strip width W is assumed small relative to ? =2 ?2/d ;? is the bulk London penetration depth of the film material and d is the film thickness.

Kogan, V. G.; Mints, R. G.

2014-11-01

418

Optical Properties of ZnS Thin Films  

Microsoft Academic Search

Zinc sulfide (ZnS) thin films of different thickness were deposited on Corning 7059 glass substrate at room temperature and high vacuum using resistive heating technique. The film properties investigated include their absorbance \\/ transmittance \\/ reflectance spectra, band gap, refractive index, extinction coefficient, optical conductivity, complex dielectric constant and thickness. The films were found to exhibit high transmittance (60-99%), low

M. Y. Nadeem; Waqas Ahmed

2000-01-01

419

THIN-FILM -LIMIT OF THE MICROMAGNETIC FREE ENERGY  

E-print Network

using films for computer data storage and solar cells, a deep understanding of the ferromagneticTHIN-FILM -LIMIT OF THE MICROMAGNETIC FREE ENERGY CAROLIN KREISBECK Abstract. The asymptotic behavior of the micromagnetic free energy gov- erning a ferromagnetic film is studied as its thickness gets

420

Optimization of Chemical Bath Deposited Cadmium Sulfide Thin Films  

Microsoft Academic Search

We report the optimization of CdS thin film grown by chemical bath deposition where homogenous reactions are min- imized. The optimum parameters have enabled us to maximize the thickness of the deposited film in a single dip and to grow thicker films by periodically replenishing the concentration of reactants while the substrate remains continuously dipped in the reaction bath. Characterization

R. C. Weast; Teil B; Verlag Chemie; Lee Chow

421

Improved process for making thin-film sodium niobate capacitors  

NASA Technical Reports Server (NTRS)

Sodium niobate, formed by high vacuum, flash, and reactive evaporations, has a high dielectric constant and is used as a thin film dielectric in microelectronic capacitors. High purity films are formed from relatively inexpensive, pure starting materials. Crystalline sodium niobate films can be formed on amorphous or crystalline materials.

Micka, E. Z.

1968-01-01

422

Transition noise properties in longitudinal thin-film media  

Microsoft Academic Search

Transition noise properties in longitudinal thin film media are studied by micromagnetic modeling. The mechanism for enhancement of transition noise at small bit intervals due to intertransition interaction is investigated. The noise dependence on the medium parameters, such as saturation magnetization and film thickness, is calculated. Reducing either the saturation magnetization or the film thickness yields a reduction of transition

Jian-Gang Zhu

1993-01-01

423

Artificial Retina Using Thin-Film Photodiodes and Thin-Film Transistors  

NASA Astrophysics Data System (ADS)

An artificial retina using thin-film photodiodes (TFPDs) and thin-film transistors (TFTs) is proposed, which is expected to be suitable for living bodies, low-emitting and cost-effective, and which is an improvement of the system-on-panel devices in which the in-pixel and pixel-to-pixel operations are executed using TFTs. The characteristics of a TFPD and TFTs are measured, and their models are made for a circuit simulator. Circuits of the retina pixel and retina array with some improvements are invented, and it is confirmed using a circuit simulator that the artificial retina using TFPDs and TFTs can operate. Edge enhancement is also confirmed, and its dependence on the characteristic deviations of TFTs is analyzed.

Kimura, Mutsumi; Shima, Takehiro; Okuyama, Tomoyuki; Utsunomiya, Sumio; Miyazawa, Wakao; Inoue, Satoshi; Shimoda, Tatsuya

2006-05-01

424

Evaluation of Thin-Film Photodiodes and Development of Thin-Film Phototransistor  

NASA Astrophysics Data System (ADS)

First, a p/i/n thin-film photodiode (TFPD) is evaluated, and it is found that the photoinduced current (Iphoto) is relatively large. Next, a p/n TFPD is evaluated, and it is found that the Iphoto is independent of the applied voltage (Vapply). However, it is difficult to simultaneously achieve a large and independent Iphoto. Therefore, a p/i/n thin-film phototransistor (TFPT) is developed, and it is found that the Iphoto can be both relatively large and independent of the Vapply by optimizing the gate voltage. These characteristics are obtained because the depletion layer is formed in the entire intrinsic region and the electric field is always high. It is expected that these characteristics are preferable for some types of photosensor application such as artificial retina.

Yamashita, Takehiko; Shima, Takehiro; Nishizaki, Yoshitaka; Kimura, Mutsumi; Hara, Hiroyuki; Inoue, Satoshi

2008-03-01

425

Alternating-current thin-film electroluminescence  

NASA Astrophysics Data System (ADS)

Alternating-current thin-film electroluminescent (ACTFEL) phosphors have been studied and improved with respect to brightness, color and efficiency. It is shown that ex- situ co-doping of the sputter deposited ZnS:Mn active layer with K and Cl results in 53% improvement in brightness, 62% improvement in efficiency, and better 100-hour accelerated aging stability. This improvement was demonstrated to result from a 75% increase in excitation efficiency for conduction electrons, combined with a small decrease in both light outcoupling and non- radiative recombination. By studying the electrical behavior of the co-doped devices as compared to the undoped devices, it was determined that there is a reduced amount of static space charge in the films, resulting in a larger average field, increased excitation efficiency, and increased charge multiplication. The reduced space charge is attributed to the addition of charge compensating zinc vacancy-chlorine complexes and isolated chlorine point defects, which are acceptor and donor defects, respectively, and the reduction of zinc vacancy deep hole traps. It is postulated that there is sufficient electron multiplication or donor ionization to create a situation in which the current limit is set by the phosphor resistance rather than a capacitance or density of states. Thin film Zn2GeO4:Mn phosphor layers were evaluated as green-emitting ACTFEL devices. Devices with Zn2GeO 4:Mn magnetron sputter deposited films exhibited brightness and efficiency values of 74 cd/m2 and 0.19 lm/W, respectively at 40 V above threshold and 60 Hz. Poor outcoupling efficiency suggests an internal efficiency that is much higher. Optical spectroscopy reveals efficient charge transfer from the lattice and a 615 meV sub-band gap defect state to the Mn 2+ ion. Unique transient optical and electrical behavior under EL excitation is observed. A phenomenological model is presented to explain the behavior. The unique aspects of the model include a resistance-capacitance limit on charge injection, efficient charge injection for only one polarity, abnormally large space charge density for one polarity that allows efficient electron-hole pair recombination in low electric field regions, and near-resonant energy transfer to and from the Mn2+ excited state.

Lewis, John South, III

426

Superconductor films with improved flux pinning and reduced AC losses  

DOEpatents

The present invention relates to a method for producing a defect-containing superconducting film, the method comprising (a) depositing a phase-separable layer epitaxially onto a biaxially-textured substrate, wherein the phase-separable layer includes at least two phase-separable components; (b) achieving nanoscale phase separation of the phase-separable layer such that a phase-separated layer including at least two phase-separated components is produced; and (c) depositing a superconducting film epitaxially onto said phase-separated components of the phase-separated layer such that nanoscale features of the phase-separated layer are propagated into the superconducting film.

Goyal, Amit (Knoxville, TN)

2011-04-05

427

Effect of a superconductor film placed in a rectangular waveguide on the principal-mode propagation conditions in the waveguide  

NASA Astrophysics Data System (ADS)

The paper presents an analysis of the effect of the S-to-N (superconducting-to-normal state) switching of a superconductor film placed in a rectangular waveguide on the principal-mode propagation conditions in the waveguide. Results are presented on the frequency dependence of the surface resistance for niobium and niobium nitride films for the N and S states. The results obtained can be used to evaluate the feasibility of using metallic superconductor films to construct microwave waveguide-type switching devices operating on the basis of the S-to-N switching principle.

Vendik, O. G.; Bel'Ski, M.; Gaidukov, M. M.; Kozyrev, A. B.; Popov, A. Iu.

1987-10-01

428

Thin films of mixed metal compounds  

DOEpatents

Disclosed is a thin film heterojunction solar cell, said heterojunction comprising a p-type I-III-IV[sub 2] chalcopyrite substrate and an overlying layer of an n-type ternary mixed metal compound wherein said ternary mixed metal compound is applied to said substrate by introducing the vapor of a first metal compound to a vessel containing said substrate from a first vapor source while simultaneously introducing a vapor of a second metal compound from a second vapor source of said vessel, said first and second metals comprising the metal components of said mixed metal compound; independently controlling the vaporization rate of said first and second vapor sources; reducing the mean free path between vapor particles in said vessel, said gas being present in an amount sufficient to induce homogeneity of said vapor mixture; and depositing said mixed metal compound on said substrate in the form of a uniform composition polycrystalline mixed metal compound. 5 figs.

Mickelsen, R.A.; Chen, W.S.

1985-06-11

429

Characterization of lithium phosphorous oxynitride thin films  

SciTech Connect

Electrical and electrochemical properties of an amorphous thin-film lithium electrolyte, lithium phosphorous oxynitride (Lipon), have been studied with emphasis on the stability window vs Li metal and the behavior of the Li/Lipon interface. Ion conductivity of Lipon exhibits Arrhenius behavior at {minus}26 to +140 C, with a conductivity of 1.7 {times} 10{sup {minus}6}S/cm at 25 C and an activity energy of 0.50 {plus_minus} 0.01 eV. A stability window of 5.5 V was observed with respect to a Li{sup +}/Li reference, and no detectable reaction or degradation was evident at the Li/Lipon interface upon lithium cycling.

Yu, Xiaohua; Bates, J.B.; Jellison, G.E. Jr.

1996-01-01

430

Nonlinear optics of astaxanthin thin films  

NASA Astrophysics Data System (ADS)

Carotinoids exhibit large nonlinear optical properties due to their extended (pi) -electron system. Compared to other polyenes which show a broad distribution of conjugation lengths, carotinoids exhibit a well defined molecular structure, i.e. a well defined conjugation length. Therefore the carotinoid molecules can serve as model compounds to study the relationship between structure and nonlinear optical properties. In this paper the synthesis of four astaxanthins with C-numbers ranging from 30 to 60, their preparation into thin films, wavelength dispersive Third Harmonic Generation (THG) measurements and some molecular modelling calculations will be presented. Resonant (chi) (3) values reach 1.2(DOT)10-10 esu for C60 astaxanthin. In the nonresonant regime a figure of merit (chi) (3)/(alpha) of several 10-13 esu-cm is demonstrated.

Esser, A.; Fisch, Herbert; Haas, Karl-Heinz; Haedicke, E.; Paust, J.; Schrof, Wolfgang; Ticktin, Anton

1993-02-01

431

Transparent Conductive Oxides in Thin Film Photovoltaics  

NASA Astrophysics Data System (ADS)

This paper show results from the development of transparent conductive oxides (TCO's) on large areas for the use as front electrode in thin film silicon solar modules. It is focused on two types of zinc oxide, which are cheap to produce and scalable to a substrate size up to 6 m2. Low pressure CVD with temperatures below 200°C can be used for the deposition of boron doped ZnO with a native surface texture for good light scattering, while sputtered aluminum doped ZnO needs a post deposition treatment in an acid bath for a rough surface. The paper presents optical and electrical characterization of large area samples, and also results about long term stability of the ZnO samples with respect to the so called TCO corrosion.

Hamelmann, Frank U.

2014-11-01

432

Structure of Thin-Film Lithium Microbatteries  

NASA Technical Reports Server (NTRS)

A process for making thin-film batteries including the steps of cleaning a glass or silicon substrate having an amorphous oxide layer several microns thick; defining with a mask the layer shape when depositing cobalt as an adhesion layer and platinum as a current collector; using the same mask as the preceding step to sputter a layer of LiC(0)O2, on the structure while rocking it back and forth; heating the substrate to 300 C. for 30 minutes; sputtering with a new mask that defines the necessary electrolyte area; evaporating lithium metal anodes using an appropriate shadow mask; and, packaging the cell in a dry-room environment by applying a continuous bead of epoxy around the active cell areas and resting a glass slide over the top thereof. The batteries produced by the above process are disclosed.

Whitacre, Jay F. (Inventor); Bugga, Ratnakumar V. (Inventor); West, William C. (Inventor)

2003-01-01

433

Thin-film evaporator recovers solvents continuously  

SciTech Connect

Reclaimed Energy Company, Inc., Connersville, IN, receives waste generated from a wide variety of industrial applications which include paint, printing and degreasing companies. The wastes are stored in separate tanks and then distilled in batches (pot distillation). The recovered solvents can be returned to the originator. The residue, left after the solvents are distilled, is disposed of using an environmentally safe, economical procedure. The company worked with an engineering and fabrication firm to develop a continuous processing system that employs a mechanically agitated thin-film evaporator to distill the solvents. Successful performance of the evaporator was ensured by processing samples of solvents through the evaporator manufacturer's pilot plant facilities before the full-sized system was designed. Reclaimed Energy Company, Inc., has realized a number of advantages by going from pot distillation to the agitated thin-film evaporator system to distill solvents. First, distillation no longer generates wastewater and no water is added to the distillate. Second, a feed tank of any size can be hooked up and run on a continuous basis until that tank is empty. Third, the residue can be kept fluid and is free of water so that it can be sold as a chemical fuel. Fourth, the high-boiling solvents can be distilled under vacuum, reducing thermal degradation and improving operating efficiency. Fifth, the residence time in the evaporator is extremely short. The extensive automatic controls installed on the skid make the equipment very versatile. The evaporator can be used to run many different products with a minimum of changes requiring operator attention.

Roembke, R.; Mode, J.; Hodel, A.E.

1985-11-01

434

Magnetic Characteristics of Copper Ion-Modified DNA Thin Films  

PubMed Central

We developed a new method of fabricating a divalent copper ion (Cu2+) modified DNA thin film on a glass substrate and studied its magnetic properties. We evaluated the coercive field (Hc), remanent magnetization (Mr), susceptibility (?), and thermal variation of magnetization with varying Cu2+ concentrations [Cu2+] resulting in DNA thin films. Although thickness of the two dimensional DNA thin film with Cu2+ in dry state was extremely thin (0.6?nm), significant ferromagnetic signals were observed at room temperature. The DNA thin films with a [Cu2+] near 5?mM showed the distinct S-shape hysteresis with appreciable high Hc, Mr and ? at low field (?600?Oe). These were primarily caused by the presence of small magnetic dipoles of Cu2+ coordination on the DNA molecule, through unpaired d electrons interacting with their nearest neighbors and the inter-exchange energy in the magnetic dipoles making other neighboring dipoles oriented in the same direction. PMID:23660965

Dugasani, Sreekantha Reddy; Lee, Namhoon; Lee, Junwye; Kim, Byeonghoon; Hwang, Si Un; Lee, Keun Woo; Kang, Won Nam; Park, Sung Ha

2013-01-01

435

Structural stability and phase transitions in WO3 thin films.  

PubMed

Tungsten oxide (WO3) thin films have been produced by KrF excimer laser (lambda = 248 nm) ablation of bulk ceramic WO3 targets. The crystal structure, surface morphology, chemical composition, and structural stability of the WO3 thin films have been studied in detail. Characterization of freshly grown WO3 thin films has been performed using X-ray diffraction (XRD), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy (RS), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) measurements. The results indicate that the freshly grown WO3 thin films are nearly stoichiometric and well crystallized as monoclinic WO3. The surface morphology of the resulting WO3 thin film has grains of approximately 60 nm in size with a root-mean-square (rms) surface roughness of 10 nm. The phase transformations in the WO3 thin films were investigated by annealing in the TEM column at 30-500 degrees C. The phase transitions in the WO3 thin films occur in sequence as the temperature is increased: monoclinic --> orthorhombic --> hexagonal. Distortion and tilting of the WO6 octahedra occurs with the phase transitions and significantly affects the electronic properties and, hence, the electrochemical device applications of WO3. PMID:16722749

Ramana, C V; Utsunomiya, S; Ewing, R C; Julien, C M; Becker, U

2006-06-01

436

Thin film thermocouples for high temperature measurement on ceramic materials  

NASA Technical Reports Server (NTRS)

Thin film thermocouples have been developed for use on metal parts in jet engines to 1000 C. However, advanced propulsion systems are being developed that will use ceramic materials and reach higher temperatures. The purpose of this work is to develop thin film thermocouples for use on ceramic materials. The thin film thermocouples are Pt13Rh/Pt fabricated by the sputtering process. Lead wires are attached using the parallel-gap welding process. The ceramic materials are silicon nitride, silicon carbide, aluminum oxide, and mullite. Both steady state and thermal cycling furnace tests were performed in the temperature range to 1500 C. High-heating-rate tests were performed in an arc lamp heat-flux-calibration facility. The fabrication of the thin film thermocouples is described. The thin film thermocouple output was compared to a reference wire thermocouple. Drift of the thin film thermocouples was determined, and causes of drift are discussed. The results of high-heating-rate tests up to 2500 C/sec are presented. The stability of the ceramic materials is examined. It is concluded that Pt13Rh/Pt thin film thermocouples are capable of meeting lifetime goals of 50 hours or more up to temperatures of 1500 C depending on the stability of the particular ceramic substrate.

Holanda, Raymond

1992-01-01

437

thin films grown with additional NaF layers  

NASA Astrophysics Data System (ADS)

CZTS precursors [SLG/Mo (300 nm)/ZnS (460 nm)/SnS (480 nm)/Cu (240 nm)] were deposited by RF/DC sputtering, and then NaF layers (0, 15, and 30 nm) were grown by electron beam evaporation. The precursors were annealed in a furnace with Se metals at 590°C for 20 minutes. The final composition of the CZTSSe thin-films was of Cu/(Zn + Sn) ~ 0.88 and Zn/Sn ~ 1.05, with a metal S/Se ratio estimated at ~0.05. The CZTSSe thin-films have different NaF layer thicknesses in the range from 0 to 30 nm, achieving a ~3% conversion efficiency, and the CZTSSe thin-films contain ~3% of Na. Kelvin probe force microscopy was used to identify the local potential difference that varied according to the thickness of the NaF layer on the CZTSSe thin-films. The potential values at the grain boundaries were observed to increase as the NaF thickness increased. Moreover, the ratio of the positively charged GBs in the CZTSSe thin-films with an NaF layer was higher than that of pure CZTSSe thin-films. A positively charged potential was observed around the grain boundaries of the CZTSSe thin-films, which is a beneficial characteristic that can improve the performance of a device.

Kim, Gee Yeong; Kim, Juran; Jo, William; Son, Dae-Ho; Kim, Dae-Hwan; Kang, Jin-Kyu

2014-10-01

438

Thin-film sensors for space propulsion technology  

NASA Astrophysics Data System (ADS)

SSME components such as the turbine blades of the high pressure fuel turbopump are subjected to rapid and extreme thermal transients that contribute to blade cracking and subsequent failure. The objective was to develop thin film sensors for SSME components. The technology established for aircraft gas turbine engines was adopted to the materials and environment encountered in the SSME. Specific goals are to expand the existing thin film sensor technology, to continue developing improved sensor processing techniques, and to test the durability of aircraft gas turbine engine technology in the SSME environment. A thin film sensor laboratory is being installed in a refurbished clean room, and new sputtering and photoresist exposure equipment is being acquired. Existing thin film thermocouple technology in an SSME environment are being tested. Various coatings and their insulating films are being investigated for use in sensor development.

Kim, W. S.; Englund, D. R.

1985-05-01

439

Bi(111) thin film with insulating interior but metallic surfaces.  

PubMed

The electrical conductance of epitaxial Bi thin films grown on BaF(2)(111) by molecular beam epitaxy has been systematically investigated as a function of both film thickness (4-540 nm) and temperature (5-300 K). Unlike bulk Bi as a prototypical semimetal, the Bi thin films up to 90 nm are found to be insulating in the interior but metallic on the surface. This finding not only has unambiguously resolved the long-standing controversy about the existence of the semimetal-semiconductor transition in Bi thin films but also provided a straightforward interpretation for the perplexing temperature dependence of the resistivity of Bi thin films, which in turn might have some potential applications in spintronics. PMID:23215113

Xiao, Shunhao; Wei, Dahai; Jin, Xiaofeng

2012-10-19

440

Thin-film Sensors for Space Propulsion Technology  

NASA Technical Reports Server (NTRS)

SSME components such as the turbine blades of the high pressure fuel turbopump are subjected to rapid and extreme thermal transients that contribute to blade cracking and subsequent failure. The objective was to develop thin film sensors for SSME components. The technology established for aircraft gas turbine engines was adopted to the materials and environment encountered in the SSME. Specific goals are to expand the existing thin film sensor technology, to continue developing improved sensor processing techniques, and to test the durability of aircraft gas turbine engine technology in the SSME environment. A thin film sensor laboratory is being installed in a refurbished clean room, and new sputtering and photoresist exposure equipment is being acquired. Existing thin film thermocouple technology in an SSME environment are being tested. Various coatings and their insulating films are being investigated for use in sensor development.

Kim, W. S.; Englund, D. R.

1985-01-01

441

Method for making surfactant-templated thin films  

DOEpatents

An evaporation-induced self-assembly method to prepare a porous, surfactant-templated, thin film by mixing a silica sol, a solvent, a surfactant, and an interstitial compound, evaporating a portion of the solvent to form a liquid, crystalline thin film mesophase material, and then removal of the surfactant template. Coating onto a substrate produces a thin film with the interstitial compound either covalently bonded to the internal surfaces of the ordered or disordered mesostructure framework or physically entrapped within the ordered or disordered mesostructured framework. Particles can be formed by aerosol processing or spray drying rather than coating onto a substrate. The selection of the interstitial compound provides a means for developing thin films for applications including membranes, sensors, low dielectric constant films, photonic materials and optical hosts.

Brinker, C. Jeffrey (Albuquerque, NM); Lu, Yunfeng (San Jose, CA); Fan, Hongyou (Albuquerque, NM)

2002-01-01

442

Method for making surfactant-templated thin films  

DOEpatents

An evaporation-induced self-assembly method to prepare a porous, surfactant-templated, thin film by mixing a silica sol, a solvent, a surfactant, and an interstitial compound, evaporating a portion of the solvent to form a liquid, crystalline thin film mesophase material, and then removal of the surfactant template. Coating onto a substrate produces a thin film with the interstitial compound either covalently bonded to the internal surfaces of the ordered or disordered mesostructure framework or physically entrapped within the ordered or disordered mesostructured framework. Particles can be formed by aerosol processing or spray drying rather than coating onto a substrate. The selection of the interstitial compound provides a means for developing thin films for applications including membranes, sensors, low dielectric constant films, photonic materials and optical hosts.

Brinker, C. Jeffrey (Albuquerque, NM); Lu, Yunfeng (New Orleans, LA); Fan, Hong You (Albuquerque, NM)

2010-08-31

443

The origin of haze in CVD tin oxide thin films  

NASA Astrophysics Data System (ADS)

The origin of haze was investigated in antimony-doped tin oxide thin films, and in double-stack thin films of fluorine-doped tin oxide/antimony-doped tin oxide, both deposited by chemical vapor deposition onto soda-lime-silica float glass substrates. These transparent conductive oxide thin films are of great importance in the production of solar control architectural glazing units. Therefore, understanding the origins of haze is necessary to the development of coated, IR-reflecting glass windows with low overall haze levels. Haze measurements of as-prepared and polished samples were correlated with surface roughness and concentration of internal hole defects. Surface roughnesses were evaluated by atomic force microscopy, and characterized by estimated RMS values. In thin tin oxide films (<2000 Å) internal hole defects caused haze, while in thick tin oxide films (>4000 Å) surface roughness was the primary source of haze.

Szanyi, János

2002-01-01

444

Optical and Structural Properties of Ultra-thin Gold Films  

E-print Network

Realizing laterally continuous ultra-thin gold films on transparent substrates is a challenge of significant technological importance. In the present work, formation of ultra-thin gold films on fused silica is studied, demonstrating how suppression of island formation and reduction of plasmonic absorption can be achieved by treating substrates with (3-mercaptopropyl) trimethoxysilane prior to deposition. Void-free fi lms with deposition thickness as low as 5.4 nm are realized and remain structurally stable at room temperature. Based on detailed structural analysis of the fi lms by specular and diffuse X-ray reflectivity measurements, it is shown that optical transmission properties of continuous ultra-thin films can be accounted for using the bulk dielectric function of gold. However, it is important to take into account the non-abrupt transition zone between the metal and the surrounding dielectrics, which extends through several lattice constants for the laterally continuous ultra-thin films (film thickness...

Kossoy, Anna; Simakov, Denis; Leosson, Kristjan; Kéna-Cohen, Stéphane; Maier, Stefan A

2014-01-01

445

X-ray diffraction characterization of thin superconductive films  

SciTech Connect

The physical and mechanical properties of thin films are often different from the properties of bulk material and are dictated by the film/substrate orientation relationship, crystal anisotropy and crystalgraphic texture of the film. X-ray diffraction texture analysis provides information about preferential film growth and can be used for optimization of deposition parameters and prediction of properties of thin films. An x-ray back reflection technique using the Braga-Brentano geometry with experimental corrections for absorption and defocusing was used to study thin ceramic films deposited by combustion chemical vapor deposition (CCVD). The film/substrate orientation relationships of YBa{sub 2}Cu{sub 3}O{sub x} (YBCO) superconducting thin films deposited via CCVD on single crystal MgO and polycrystalline silver substrates were studied. The as-deposited films on single crystal (100) MgO substrates showed strong preferential growth with the basal plane parallel to the substrate surface (c-axis up growth). Texture analysis showed two in-plane alignment orientations of the film with respect to the substrate, with YBCO [100] and [110] aligned with the [100] MgO substrate. YBCO films deposited on cold-rolled polycrystalline silver displayed c-axis up growth indicating that the orientation of the polycrystalline substrate (brass type texture) did not induce detectable in-plane preferential growth of the YBCO.

Kozaczek, K.J.; Watkins, T.R. [Oak Ridge National Lab., TN (United States); Book, G.W.; Carter, W.B. [Georgia Institute of Technology, Atlanta, GA (United States). School of Materials Science and Engineering

1995-12-31

446

Carbon nanotube based nanostructured thin films: preparation and application  

NASA Astrophysics Data System (ADS)

Hybrid thin films of multi-walled carbon nanotube (MWCNT) and titania were fabricated on quartz slides by alternatively depositing MWCNT and titanium(IV) bis(ammonium lactato) dihydroxide (TALH) via a solution based layer-by-layer (LbL) self-assembly method followed by calcination to convert TALH to crystalline titania. The multilayer film build-up was monitored by UV-vis spectroscopy which indicated the linear growth of the film with the bilayer number. XRD confirmed the formation of anantase titania after heat treatment. The photocatalytic property of the hybrid thin film was evaluated by its capacity to degrade rhodamine B under the UV illumination. Compared with pure TiO2 film, experiments showed that the MWCNT/TiO2 hybrid film had a much higher photocatalytic activity under the same conditions. The first order rate constant of photocatalysis of 30 bilayers of hybrid film was approximately 8-fold higher than that of 30 bilayers of pure TiO2 film. In addition, the degradation efficiency of MWCNT/TiO2 hybrid thin film increased with its thickness while pure titania film remained unchanged. A 30 bilayers hybrid thin film that contains about 0.2 mg MWCNT/TiO2 catalyst was capable of completely degrading 10 mL of 2 mg/L Rh B solution within 5 hours. The results also indicated that the hybrid catalyst could be reused for several cycles.

Fu, Li; Yu, Aimin

2013-08-01

447

Suppression of Copper Thin Film Loss during Graphene Synthesis.  

PubMed

Thin metal films can be used to catalyze the growth of nanomaterials in place of the bulk metal, while greatly reducing the amount of material used. A big drawback of copper thin films (0.5-1.5 ?m thick) is that, under high temperature/vacuum synthesis, the mass loss of films severely reduces the process time due to discontinuities in the metal film, thereby limiting the time scale for controlling metal grain and film growth. In this work, we have developed a facile method, namely "covered growth" to extend the time copper thin films can be exposed to high temperature/vacuum environment for graphene synthesis. The key to preventing severe mass loss of copper film during the high temperature chemical vapor deposition (CVD) process is to have a cover piece on top of the growth substrate. This new "covered growth" method enables the high-temperature annealing of the copper film upward of 4 h with minimal mass loss, while increasing copper film grain and graphene domain size. Graphene was then successfully grown on the capped copper film with subsequent transfer for device fabrication. Device characterization indicated equivalent physical, chemical, and electrical properties to conventional CVD graphene. Our "covered growth" provides a convenient and effective solution to the mass loss issue of thin films that serve as catalysts for a variety of 2D material syntheses. PMID:25552194

Lee, Alvin L; Tao, Li; Akinwande, Deji

2015-01-28

448

Multi-modal sensing using photoactive thin films  

NASA Astrophysics Data System (ADS)

The need for a reliable prognosis of the health of structural systems has promoted the development of sensing technologies capable of simultaneously detecting multiple types of damage. However, conventional sensors are designed to only measure a specific structural response (e.g., strain, displacement, or acceleration). This limitation forces one to use a wide variety of sensors densely instrumented on a given structure, which results in high overhead costs and requires extensive signal processing of raw sensor data. In this study, a photoactive thin film that has been engineered for multi-modal sensing to selectively detect strain and pH is proposed. In addition, the thin film is self-sensing in that it does not require external power to operate. Instead, light illumination causes the photoactive film to generate an electrical current, whose magnitude is directly related to applied strains (for deformations, impact or cracks) or pH (as a precursor of corrosion). First, the thin films were fabricated by spin-coating photoactive and conjugated polymers like poly(3-hexylthiophene) (P3HT). The thin film was also encoded with pH sensitivity by integrating polyaniline (PANI) as one component within the multilayered film architecture. Second, the optical response of the P3HT and PANI thin films subjected to applied strains or pH was characterized using absorption spectroscopy. Lastly, it was also verified that the thin films could selectively sense strain or pH depending on the wavelengths of light used for sensor interrogation.

Ryu, Donghyeon; Loh, Kenneth J.

2014-08-01

449

Properties of Ba-hexaferrite thin films with different thicknesses  

NASA Astrophysics Data System (ADS)

M-type Ba-hexaferrite (BaM) thin films with different thicknesses were deposited on (0 0 1) Al2O3 substrates by RF magnetron sputtering. Effects of film thickness on the crystallographic, morphological and magnetic properties were investigated. Experimental results showed that properties of BaM thin films are strongly dependent on thickness and thinner film favors to obtain better (0 0 l) planes orientation with narrower XRD FWHM. The 150-nm thick film possesses columnar-type grains having c-axis orientation perpendicular to the film plane. However, with the thickness increasing from 150 to 550 nm, acicular-type grain increases. Thus, the texture of (0 0 l) planes orientation of the film deteriorates; the saturation magnetization and perpendicular magnetocrystalline anisotropy also decrease gradually. Mechanisms for these variations are attributed to the increase of random nucleation sites and strain relaxation in the films with increasing thickness.

Xu, Zhiyong; Lan, Zhongwen; Sun, Ke; Guo, Rongdi; Yu, Zhong; Jiang, Xiaona; Zhu, Guangwei

2013-04-01

450

Photoinduced conductivity in tin dioxide thin films  

SciTech Connect

The effects of ultraviolet light irradiation on the conducting properties of SnO{sub 2-x} thin films grown epitaxially on TiO{sub 2} or Al{sub 2}O{sub 3} single-crystal substrates are studied at room temperature. A large increase in conductivity by two to four orders of magnitude is observed with light irradiation in an inert atmosphere and remains after the light is removed. The high-conducting state reverts to the original low-conducting state by exposing it to oxygen gas. These reversible phenomena are ascribed to the desorption and adsorption of negatively charged oxygen species at the grain boundaries, which critically change the mobility of electron carriers already present inside grains by changing the potential barrier height at the grain boundary. The UV light irradiation provides us with an easy and useful route to achieve a high-conducting state even at low carrier density in transparent conducting oxides and also to draw an invisible conducting wire or a specific pattern on an insulating film.

Muraoka, Y.; Takubo, N.; Hiroi, Z. [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)

2009-05-15

451

Transparent conducting thin films for spacecraft applications  

NASA Technical Reports Server (NTRS)

Transparent conductive thin films are required for a variety of optoelectronic applications: automotive and aircraft windows, and solar cells for space applications. Transparent conductive coatings of indium-tin-oxide (ITO)-magnesium fluoride (MgF2) and aluminum doped zinc oxide (AZO) at several dopant levels are investigated for electrical resistivity (sheet resistance), carrier concentration, optical properties, and atomic oxygen durability. The sheet resistance values of ITO-MgF2 range from 10(exp 2) to 10(exp 11) ohms/square, with transmittance of 75 to 86 percent. The AZO films sheet resistances range from 10(exp 7) to 10(exp 11) ohms/square with transmittances from 84 to 91 percent. It was found that in general, with respect to the optical properties, the zinc oxide (ZnO), AZO, and the high MgF2 content ITO-MgF2 samples, were all durable to atomic oxygen plasma, while the low MgF2 content of ITO-MgF2 samples were not durable to atomic oxygen plasma exposure.

Perez-Davis, Marla E.; Malave-Sanabria, Tania; Hambourger, Paul; Rutledge, Sharon K.; Roig, David; Degroh, Kim K.; Hung, Ching-Cheh

1994-01-01

452

Germanium Lift-Off Masks for Thin Metal Film Patterning  

NASA Technical Reports Server (NTRS)

A technique has been developed for patterning thin metallic films that are, in turn, used to fabricate microelectronics circuitry and thin-film sensors. The technique uses germanium thin films as lift-off masks. This requires development of a technique to strip or undercut the germanium chemically without affecting the deposited metal. Unlike in the case of conventional polymeric lift-off masks, the substrate can be exposed to very high temperatures during processing (sputter deposition). The reason why polymeric liftoff masks cannot be exposed to very high temperatures (greater than 100 C) is because (a) they can become cross linked, making lift-off very difficult if not impossible, and (b) they can outgas nitrogen and oxygen, which then can react with the metal being deposited. Consequently, this innovation is expected to find use in the fabrication of transition edge sensors and microwave kinetic inductance detectors, which use thin superconducting films deposited at high temperature as their sensing elements. Transition edge sensors, microwave kinetic inductance detectors, and their circuitry are comprised of superconducting thin films, for example Nb and TiN. Reactive ion etching can be used to pattern these films; however, reactive ion etching also damages the underlying substrate, which is unwanted in many instances. Polymeric lift-off techniques permit thin-film patterning without any substrate damage, but they are difficult to remove and the polymer can outgas during thin-film deposition. The outgassed material can then react with the film with the consequence of altered and non-reproducible materials properties, which, in turn, is deleterious for sensors and their circuitry. The purpose of this innovation was to fabricate a germanium lift-off mask to be used for patterning thin metal films.

Brown, Ari

2012-01-01

453

Robust topological surface state in Kondo insulator SmB6 thin films  

NASA Astrophysics Data System (ADS)

Fabrication of smooth thin films of topological insulators with true insulating bulk are extremely important for utilizing their novel properties in quantum and spintronic devices. Here, we report the growth of crystalline thin films of SmB6, a topological Kondo insulator with true insulating bulk, by co-sputtering both SmB6 and B targets. X-ray diffraction, Raman spectroscopy, and transmission electron microscopy indicate films that are polycrystalline with a (001) preferred orientation. When cooling down, resistivity ? shows an increase around 50 K and saturation below 10 K, consistent with the opening of the hybridization gap and surface dominated transport, respectively. The ratio ?2K/?300K is only about two, much smaller than that of bulk, which indicates a much larger surface-to-bulk ratio. Point contact spectroscopy using a superconductor tip on SmB6 films shows both a Kondo Fano resonance and Andeev reflection, indicating an insulating Kondo lattice with metallic surface states.

Yong, Jie; Jiang, Yeping; Usanmaz, Demet; Curtarolo, Stefano; Zhang, Xiaohang; Li, Linze; Pan, Xiaoqing; Shin, Jongmoon; Takeuchi, Ichiro; Greene, Richard L.

2014-12-01

454

Organosilicon thin film deposition in glow discharges  

SciTech Connect

Thin films have been deposited from hexamethyldisiloxane-oxygen fed radio-frequency glow discharges under the following conditions: O{sub 2}-to-HMDS ratio ranging from 0 to 20, fixed total flow rate of 15 sccm, 200 W input power, 100 mTorr pressure. The substrates are held at room temperature. The effect of oxygen-to-monomer ratio in the feed on both plasma species distribution and film chemical composition has been studied with a variety of diagnostics, i.e. Actinometric Optical Emission Spectroscopy, AOES, (plasma phase), Infrared Spectroscopy and Electron Spectroscopy for Chemical Analysis, ESCA, (surface). A mechanism of deposition is proposed, based on the role of Si-containing precursors and of SiO-containing ones, which accounts for the deposition rate and the film composition. The experimental apparatus consists of a stainless-steel parallel plate reactor with a 13.56 MHz rf power. Silicon substrates are positioned in the gap between the two electrodes on a grounded stainless-steel holder. Deposition rates have been evaluated, after each experiment, by means of gravimetric measurements. The optical emission from the discharges has been sampled through a quartz window and focused on the entrance slit of a 1 m focal length Jarrel-Ash monochromator. The relative concentration trends of Si, O, H, and C atoms and of SiO, OH, CH, and CO molecules in plasma phase, have been obtained by AOES as a function of feed composition, by utilizing Ar and He actinometers. ESCA analyses have been performed by means of a PHI 5300 Perkin Elmer spectrometer used in the fixed analyser transmission mode with pass ene of 35.75 eV.

d`Agostino, R.; Lamendola, R. [Universita di Bari (Italy)

1995-12-31

455

Investigation of heteroepitaxial growth of magnetite thin films  

Microsoft Academic Search

Epitaxial magnetite (FeO) thin films were deposited by molecular beam epitaxy using molecular oxygen as the oxidant. Films deposited on (001) SrTiO, (001) MgO, and (001) BaTiO surfaces are epitaxial with the film (001) parallel to the substrate (001) and the film <100> parallel to the substrate <100>. X-ray magnetic circular dichroism was used to determine the relative Fe{sup 2+}\\/Fe{sup

G. E. Sterbinsky; J. Cheng; P. T. Chiu; B. W. Wessels; D. J. Keavney

2007-01-01

456

Polydimethylsiloxane thin film characterization using all-optical photoacoustic mechanism.  

PubMed

This paper presents a nondestructive ultrasound testing method for characterization of the resonant frequencies of polydimethylsiloxane (PDMS) thin film by using a miniature fiber optic photoacoustic (PA) probe. The PA probe was fabricated with an optical fiber and a synthesized gold nanocomposite. During the experiment, a cured PDMS thin film with a thickness of 220 ?m was immersed into a water medium using a custom-designed holder to clamp the film. An acoustic pulse was generated by the PA probe and propagated through the water media to excite the fixed film. A fiber optic pressure sensor based on the Fabry-Perot principle was used to collect the excited acoustic signals on the other side of the film. The acquired response of the acoustic pulse was used to compute the resonant frequencies of the PDMS thin film based on a deconvolution method. PMID:24085082

Zou, Xiaotian; Wu, Nan; Tian, Ye; Zhang, Yang; Wang, Xingwei

2013-09-01

457

Sensitive 3-omega measurements on epitaxial thermoelectric thin films  

NASA Astrophysics Data System (ADS)

Here we present a work on the development of a sensitive 3-omega instrumentation adapted for the measurement of the thermal conductivity of epitaxial thin films. The experimental setup has been validated by the measurements on an epitaxial germanium nanostructured thin film. This manganese doped germanium matrix contains Ge3Mn5 nanoinclusions having a diameter of 5 to 50 nm, grown by Molecular Beam Epitaxy (MBE). The 3 omega measurements have revealed that the thermal conductivity of GeMn nanostructured thin films can be decreased by a factor of ten as compared to the bulk value.

Liu, Y. Q.; Tainoff, D.; Boukhari, M.; Richard, J.; Barski, A.; Bayle-Guillemaud, P.; Hadji, E.; Bourgeois, O.

2014-11-01

458

Electrospray aerosol deposition of water soluble polymer thin films  

NASA Astrophysics Data System (ADS)

We report the fabrication and characterization of thin films from the water soluble polymer sodium poly[2-(3-thienyl)-ethyloxy-4-butylsulfonate] (PTEBS) by electrospray deposition (ESD). Contiguous thin films were created by adjusting the parameters of the electrospray apparatus and solution properties to maintain a steady Taylor cone for uniform nanoparticle aerosolization and controlling the particle water content to enable coalescence with previously deposited particles. The majority of deposited particles had diameters less than 52 nm. A thin film of 64.7 nm with a root mean square surface roughness of 20.2 nm was achieved after 40 min of ESD.

Sweet, Marshall L.; Pestov, Dmitry; Tepper, Gary C.; McLeskey, James T.

2014-01-01

459

Thermoelastic response of thin metal films and their adjacent materials  

SciTech Connect

A pulsed laser beam applied to a thin metal film is capable of launching an acoustic wave due to thermal expansion. Heat transfer from the thin metal film to adjacent materials can also induce thermal expansion; thus, the properties of these adjacent materials (as well as the thin metal film) should be considered for a complete description of the thermoelastic response. Here, we show that adjacent materials with a small specific heat and large thermal expansion coefficient can generate an enhanced acoustic wave and we demonstrate a three-fold increase in the peak pressure of the generated acoustic wave on substitution of parylene for polydimethylsiloxane.

Kang, S.; Yoon, Y.; Kim, J.; Kim, W. [Samsung Electronics Co., Yongin-Si, 446-712 Gyeonggi-do (Korea, Republic of)] [Samsung Electronics Co., Yongin-Si, 446-712 Gyeonggi-do (Korea, Republic of)

2013-01-14

460

XRay Study of Transfer Printed Pentacene Thin Films  

SciTech Connect

We investigated the structural properties and transfer properties of pentacene thin films fabricated by thermal deposition and transfer printing onto SiO2 and plastic substrates, respectively. The dependence of the crystallite size on the printing time, temperature and pressure were measured. The increases of crystalline size were observed when pentacene thin films were printed under specific conditions, e.g. 120 deg. C and 600 psi and can be correlated with the improvement of the field effect mobility of pentacene thin-film transistors.

Shao, Y.; Solin, S. A. [Washington University in St. Louis, Center for Materials Innovation, Department of Physics, St. Louis, Missouri 63130 (United States); Hines, D. R.; Williams, E. D. [University of Maryland, Department of Physics, College Park, Maryland 20742 (United States); Laboratory for Physical Sciences, College Park, Maryland 20742 (United States)

2007-04-10

461

Development of Thin Film Ceramic Thermocouples for High Temperature Environments  

NASA Technical Reports Server (NTRS)

The maximum use temperature of noble metal thin film thermocouples of 1100 C (2000 F) may not be adequate for use on components in the increasingly harsh conditions of advanced aircraft and next generation launch technology. Ceramic-based thermocouples are known for their high stability and robustness at temperatures exceeding 1500 C, but are typically found in the form of rods or probes. NASA Glenn Research Center is investigating the feasibility of ceramics as thin film thermocouples for extremely high temperature applications to take advantage of the stability and robustness of ceramics and the non-intrusiveness of thin films. This paper will discuss the current state of development in this effort.

Wrbanek, John D.; Fralick, Gustave C.; Farmer, Serene C.; Sayir, Ali; Blaha, Charles A.; Gonzalez, Jose M.

2004-01-01

462

The pulse thermal processing of nanocrystalline silicon thin-films  

NASA Astrophysics Data System (ADS)

Pulse thermal processing (PTP) has the capability of processing thin-films and nanoparticles over broad areas utilizing high-density infrared plasma arc lamp technology. Heating rates reaching 600,000°C/s, which is orders of magnitude larger than current state-of-the-art rapid thermal annealing systems, are possible that allow controlled diffusion on the nanoscale. The ability to control heating at these levels permits processing thin-films and nanoparticles on temperature-sensitive substrates such as polymers. The PTP technique has been used to crystallize sputtered amorphous silicon thin-films on sapphire substrates.

Ott, R. D.; Kadolkar, P.; Blue, C. A.; Cole, A. C.; Thompson, G. B.

2004-10-01

463

Relaxation of ferroelectric thin films of diisopropylammonium perchlorate.  

PubMed

Molecular ferroelectric thin films are highly desirable for their easy and environmentally friendly processing, light weight, and mechanical flexibility. A thin film of diisopropylammonium perchlorate (DIPAP) processed by a spin-coating method shows a good roughness and textured structure with (101) orientation in the ferroelectric phase with a space group of P1. Simultaneously, the thin film shows ferroelectricity and ferroelectric relaxivity above room temperature, which is completely different from crystals. These properties make DIPAP a candidate in sensing, data storage, electro-optics, and molecular/flexible electronics. PMID:25583685

Zhu, Jiansheng; Gao, Kaige; Xiao, Shuyu; Qiu, Xiangbiao; Cai, Hong-Ling; Wu, X S

2015-01-28

464

Investigation of TiO{sub x} barriers for their use in hybrid Josephson and tunneling junctions based on pnictide thin films  

SciTech Connect

We tested oxidized titanium layers as barriers for hybrid Josephson junctions with high I{sub c}R{sub n}-products and for the preparation of junctions for tunneling spectroscopy. For that we firstly prepared junctions with conventional superconductor electrodes, such as lead and niobium, respectively. By tuning the barrier thickness, we were able to change the junction's behavior from a Josephson junction to tunnel-like behavior applicable for quasi-particle spectroscopy. Subsequently, we transferred the technology to junctions using Co-doped BaFe{sub 2}As{sub 2} thin films prepared by pulsed laser deposition as base electrode and evaporated Pb as counter electr